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DNS MX Question

C

ChrisUK

#1
Hello,

I am trying to get some clarification that my mx settings are OK. Mail is
sending and receiving OK but I don't think its "by-the-book"

I am running a SBS 2008 domain (lets call it mydomain.local) and I am
hosting my own email server.

I registered my domain name with fasthosts.co.uk (lets call it
mydomain.co.uk).
I have a static IP address assigned by my ISP (BT - British Telecom)
I have forwarded port 25 on my router to go to the internal IP address of my
SBS. server
On Fasthosts control panel I can set various DNS setting (A, mx, PTR etc). I
originally created an MX record to be the Static IP address of my router. I
also created an A record to point remote.mydomain.co.uk to the same static IP
address for OWA.

Having done some more research into DNS / MX records I'm beginning to think
that what i SHOULD have done is create an A record such as
mail.mydomain.co.uk and point it to my static IP, then create an MX record
pointing to mail.mydomain.co.uk.

Is this correct?

As my mail is flowing I'm reluctant to make any changes. If I do need to
change it to what I mentioned above, can I do this without any emails getting
bounced / lost?

Final question, I've read a lot of PTR records being needed more and more.
On my control panel with Fasthosts all I can create are, A, Cname, MX, AAAA
and TXT records. Will I need to contact Fasthosts and ask them to create a
PTR record for me? What do I need to have in this PTR? Sorry if that is a
dumb question but I'm just starting to learn this stuff.

Kind regards,

Chris
 

My Computer

C

Cliff Galiher - MVP

#2
Inline:

-Cliff


"ChrisUK" <ChrisUK@newsgroup> wrote in message
news:EE6D581B-19F6-4A9C-ADED-98FD5B1288B2@newsgroup

> Hello,
>
> I am trying to get some clarification that my mx settings are OK. Mail is
> sending and receiving OK but I don't think its "by-the-book"
>
> I am running a SBS 2008 domain (lets call it mydomain.local) and I am
> hosting my own email server.
>
> I registered my domain name with fasthosts.co.uk (lets call it
> mydomain.co.uk).
By not posting your real domain, you make it difficult for *us* to look and
verify. And since it is a public domain, hackers are still going to find
and scan it. Obfuscating public domains in newsgroups provides *no* added
security. Just for future reference.

> I have a static IP address assigned by my ISP (BT - British Telecom)
> I have forwarded port 25 on my router to go to the internal IP address of
> my
> SBS. server
> On Fasthosts control panel I can set various DNS setting (A, mx, PTR etc).
> I
> originally created an MX record to be the Static IP address of my router.
> I
> also created an A record to point remote.mydomain.co.uk to the same static
> IP
> address for OWA.
>
> Having done some more research into DNS / MX records I'm beginning to
> think
> that what i SHOULD have done is create an A record such as
> mail.mydomain.co.uk and point it to my static IP, then create an MX record
> pointing to mail.mydomain.co.uk.
Either/or. I prefer domain names in MX records...one less thing to change
and get cached if things have to get shuffled. I wouldn't call your setup
*wrong* though, just not optimal.

> As my mail is flowing I'm reluctant to make any changes. If I do need to
> change it to what I mentioned above, can I do this without any emails
> getting
> bounced / lost?
If you don't make any *wrong* changes then mail will flow just fine. Some
DNS servers will have the old data cached, but since your IP isn't changing,
it'll still get delivered. And new DNS queries will get the name and since
that also appears to work, you'll continue to be fine. Should be
transparent.

> Final question, I've read a lot of PTR records being needed more and more.
> On my control panel with Fasthosts all I can create are, A, Cname, MX,
> AAAA
> and TXT records. Will I need to contact Fasthosts and ask them to create a
> PTR record for me? What do I need to have in this PTR? Sorry if that is a
> dumb question but I'm just starting to learn this stuff.
Not Fasthosts. Reverse lookups work backwards, so the PTR record would
actually be owned/controlled by the owner of the IP address. In this case
BT. Again, had you posted your public IP, we could have checked for you; it
may already exist. It doesn't need to match your company, it need only
exist.

>
> Kind regards,
>
> Chris
 

My Computer

#3
ChrisUK wrote:

>
> Final question, I've read a lot of PTR records being needed more and more.
> On my control panel with Fasthosts all I can create are, A, Cname, MX, AAAA
> and TXT records. Will I need to contact Fasthosts and ask them to create a
> PTR record for me? What do I need to have in this PTR? Sorry if that is a
> dumb question but I'm just starting to learn this stuff.
>
You already know what to do, I'd add that I've known BT to be quite
difficult about PTR records, even on 'business' accounts with static IP
addresses. There will already be one of a generic kind, along the lines
of 'adsl-12-34-56-67-pool.btconnect.com', but this is not likely to
impress other mail servers. I have my own server configured to reject
SMTP connections from addresses with PTR records of this kind.

The bad news is that many mail servers, particularly those of ISPs, will
expect a 'proper' PTR record of 'example.domain.com' form, and many
(including mine) will expect there to be a valid A record for
example.domain.com which points back to the IP address. I have not found
it necessary for the PTR-A pair to match the MX record or HELO string,
as mine do not and I have no problem sending mail to AOL, which is
notoriously fussy.

Certainly two or three years ago, BT wasn't good at organising this kind
of thing. If they are still not willing to do it, then the only way you
can send mail reliably is through another mail server which is
considered 'respectable', such as an ISP's SMTP server. Check if your
account with BT includes the use of an SMTP smarthost, as it is a
facility you may want to use for other reasons.

One of my customers insisted on using BT as ISP, against my
recommendations, and took out a 'business' account. This turned out to
have no smarthost facility and a fixed IP address that had a 'generic'
PTR and was on a number of blacklists, none of which BT was prepared to
do anything about. I ended up giving him an authenticated SMTP account
on a web hosting package that I rent, to use as a smarthost. BT's
recommendation, and I kid you not, was to use Yahoo for email. I think
even today, BT subcontracts some parts of its email handling to Yahoo.

--
Joe
 

My Computer

A

Andrew M. Saucci, Jr.

#4
Actually, the "generic" reverse DNS isn't nearly as much of a
problem as having none at all. If the ISP won't update the reverse DNS, then
setting up an A record to match it and changing the settings of the SMTP
virtual server to use that identity can work. It isn't pretty, but it's
legitimate. I don't think too many spam filters care much about what your
reverse DNS is as long as it matches what the SMTP server reports as its
identity in the HELO command. After all, the identity of a server in the end
is purely arbitrary.

"Joe" <joe@newsgroup> wrote in message
news:%23LkxhPHlKHA.5128@newsgroup

> ChrisUK wrote:

>>
>> Final question, I've read a lot of PTR records being needed more and
>> more. On my control panel with Fasthosts all I can create are, A, Cname,
>> MX, AAAA and TXT records. Will I need to contact Fasthosts and ask them
>> to create a PTR record for me? What do I need to have in this PTR? Sorry
>> if that is a dumb question but I'm just starting to learn this stuff.
>>
>
> You already know what to do, I'd add that I've known BT to be quite
> difficult about PTR records, even on 'business' accounts with static IP
> addresses. There will already be one of a generic kind, along the lines of
> 'adsl-12-34-56-67-pool.btconnect.com', but this is not likely to impress
> other mail servers. I have my own server configured to reject SMTP
> connections from addresses with PTR records of this kind.
>
> The bad news is that many mail servers, particularly those of ISPs, will
> expect a 'proper' PTR record of 'example.domain.com' form, and many
> (including mine) will expect there to be a valid A record for
> example.domain.com which points back to the IP address. I have not found
> it necessary for the PTR-A pair to match the MX record or HELO string, as
> mine do not and I have no problem sending mail to AOL, which is
> notoriously fussy.
>
> Certainly two or three years ago, BT wasn't good at organising this kind
> of thing. If they are still not willing to do it, then the only way you
> can send mail reliably is through another mail server which is considered
> 'respectable', such as an ISP's SMTP server. Check if your account with BT
> includes the use of an SMTP smarthost, as it is a facility you may want to
> use for other reasons.
>
> One of my customers insisted on using BT as ISP, against my
> recommendations, and took out a 'business' account. This turned out to
> have no smarthost facility and a fixed IP address that had a 'generic' PTR
> and was on a number of blacklists, none of which BT was prepared to do
> anything about. I ended up giving him an authenticated SMTP account on a
> web hosting package that I rent, to use as a smarthost. BT's
> recommendation, and I kid you not, was to use Yahoo for email. I think
> even today, BT subcontracts some parts of its email handling to Yahoo.
>
> --
> Joe
 

My Computer

C

Cliff Galiher - MVP

#5
Just as a matter of debate, I've *never* seen a spam filter care if the
reverse DNS *or* A record matches the HELO string in a mail server. In
fact, more often than not, they don't.

Take an example of a company that uses a cloud-based email service, such as
an ISP server or hosted-Exchange. If you go the hosted-Exchange route, do
you really think MS gives you your own Exchange servers and that the HELO
strings match the MX/A record pair you set up? Or do you think that a
service provider that offers businesses 10-20 free email accounts as part of
their business bundle also gives them a dedicated server?

There are so many *legitimate* scenarios where the HELO string will NOT
match the MX record that no spam filters would rightfully reject or even
negatively score messages that have a return header with such a setup.

But what you say is true, a generic rDNS is usually perfectly adequate as
long as the ISP also has an A record that matches the PTR record so that it
is a matching pair. There isn't usually a cause to get them to create
custom/renamed records.

-Cliff


"Andrew M. Saucci, Jr." <spam-only@newsgroup> wrote in message
news:eyYMOLNlKHA.3476@newsgroup

> Actually, the "generic" reverse DNS isn't nearly as much of a
> problem as having none at all. If the ISP won't update the reverse DNS,
> then setting up an A record to match it and changing the settings of the
> SMTP virtual server to use that identity can work. It isn't pretty, but
> it's legitimate. I don't think too many spam filters care much about what
> your reverse DNS is as long as it matches what the SMTP server reports as
> its identity in the HELO command. After all, the identity of a server in
> the end is purely arbitrary.
>
> "Joe" <joe@newsgroup> wrote in message
> news:%23LkxhPHlKHA.5128@newsgroup

>> ChrisUK wrote:

>>>
>>> Final question, I've read a lot of PTR records being needed more and
>>> more. On my control panel with Fasthosts all I can create are, A, Cname,
>>> MX, AAAA and TXT records. Will I need to contact Fasthosts and ask them
>>> to create a PTR record for me? What do I need to have in this PTR? Sorry
>>> if that is a dumb question but I'm just starting to learn this stuff.
>>>
>>
>> You already know what to do, I'd add that I've known BT to be quite
>> difficult about PTR records, even on 'business' accounts with static IP
>> addresses. There will already be one of a generic kind, along the lines
>> of 'adsl-12-34-56-67-pool.btconnect.com', but this is not likely to
>> impress other mail servers. I have my own server configured to reject
>> SMTP connections from addresses with PTR records of this kind.
>>
>> The bad news is that many mail servers, particularly those of ISPs, will
>> expect a 'proper' PTR record of 'example.domain.com' form, and many
>> (including mine) will expect there to be a valid A record for
>> example.domain.com which points back to the IP address. I have not found
>> it necessary for the PTR-A pair to match the MX record or HELO string, as
>> mine do not and I have no problem sending mail to AOL, which is
>> notoriously fussy.
>>
>> Certainly two or three years ago, BT wasn't good at organising this kind
>> of thing. If they are still not willing to do it, then the only way you
>> can send mail reliably is through another mail server which is considered
>> 'respectable', such as an ISP's SMTP server. Check if your account with
>> BT includes the use of an SMTP smarthost, as it is a facility you may
>> want to use for other reasons.
>>
>> One of my customers insisted on using BT as ISP, against my
>> recommendations, and took out a 'business' account. This turned out to
>> have no smarthost facility and a fixed IP address that had a 'generic'
>> PTR and was on a number of blacklists, none of which BT was prepared to
>> do anything about. I ended up giving him an authenticated SMTP account on
>> a web hosting package that I rent, to use as a smarthost. BT's
>> recommendation, and I kid you not, was to use Yahoo for email. I think
>> even today, BT subcontracts some parts of its email handling to Yahoo.
>>
>> --
>> Joe
>
>
 

My Computer

A

Ace Fekay [MVP-DS, MCT]

#6
"Cliff Galiher - MVP" <cgaliher@newsgroup> wrote in message
news:etYJc6NlKHA.2592@newsgroup

> Just as a matter of debate, I've *never* seen a spam filter care if the
> reverse DNS *or* A record matches the HELO string in a mail server. In
> fact, more often than not, they don't.
>
> Take an example of a company that uses a cloud-based email service, such
> as an ISP server or hosted-Exchange. If you go the hosted-Exchange route,
> do you really think MS gives you your own Exchange servers and that the
> HELO strings match the MX/A record pair you set up? Or do you think that
> a service provider that offers businesses 10-20 free email accounts as
> part of their business bundle also gives them a dedicated server?
>
> There are so many *legitimate* scenarios where the HELO string will NOT
> match the MX record that no spam filters would rightfully reject or even
> negatively score messages that have a return header with such a setup.
>
> But what you say is true, a generic rDNS is usually perfectly adequate as
> long as the ISP also has an A record that matches the PTR record so that
> it is a matching pair. There isn't usually a cause to get them to create
> custom/renamed records.
>
> -Cliff

Cliff,

I understand what you're saying about not requiring a matching PTR to MX
record, but I just wanted to point out that in some spam filters, such as
Vamsoft, it is an option. Of course I never use that option due to the
scenarios you described. I would be surprised if anyone does or they would
be rejecting numerous ligitimate mail.

--
Ace

This posting is provided "AS-IS" with no warranties or guarantees and
confers no rights.

Please reply back to the newsgroup or forum for collaboration benefit among
responding engineers, and to help others benefit from your resolution.

Ace Fekay, MVP, MCT, MCITP EA, MCTS Windows 2008 & Exchange 2007, MCSE &
MCSA 2003/2000, MCSA Messaging 2003
Microsoft Certified Trainer
Microsoft MVP - Directory Services

If you feel this is an urgent issue and require immediate assistance, please
contact Microsoft PSS directly. Please check http://support.microsoft.com
for regional support phone numbers.
 

My Computer

C

ChrisUK

#7
Cliff> OK - thanks for the heads up. My domain name registered with Fasthosts
is www.zoo-hardware.co.uk. My internal domain name is zoohardware.local.
Also, thanks for confirming that for me. I've made the change to the MX
record from IP address (81.149.235.191) to mail.zoo-hardware.co.uk. I did
this several hours ago and everything seems to be working.

When I use nslookup to view a couple of other companyies who I know are
using BT their MX records show as
mail exchanger = host(ip-address).in-addr.btopenworld.com

I was just concerned that mine appears much simpler.

Also, i'd quite like a backup so if my server ever went down, mail would go
somewhere else. I would obviously put that as a higher priority. I contacted
Fasthosts about providing me with this facility but they didn't seem to offer
that service (it might have been my limited understanding of what i was
asking for!)

Joe> I know what you mean with BT, they really don't appear to be very
helpful on anything even slightly technical. I think i'll struggle to get
them to do anything for me.

Bill, Andrew and Ace> Thankyou for your input / help on this too!



"Cliff Galiher - MVP" wrote:

> Inline:
>
> -Cliff
>
>
> "ChrisUK" <ChrisUK@newsgroup> wrote in message
> news:EE6D581B-19F6-4A9C-ADED-98FD5B1288B2@newsgroup

> > Hello,
> >
> > I am trying to get some clarification that my mx settings are OK. Mail is
> > sending and receiving OK but I don't think its "by-the-book"
> >
> > I am running a SBS 2008 domain (lets call it mydomain.local) and I am
> > hosting my own email server.
> >
> > I registered my domain name with fasthosts.co.uk (lets call it
> > mydomain.co.uk).
>
> By not posting your real domain, you make it difficult for *us* to look and
> verify. And since it is a public domain, hackers are still going to find
> and scan it. Obfuscating public domains in newsgroups provides *no* added
> security. Just for future reference.
>

> > I have a static IP address assigned by my ISP (BT - British Telecom)
> > I have forwarded port 25 on my router to go to the internal IP address of
> > my
> > SBS. server
> > On Fasthosts control panel I can set various DNS setting (A, mx, PTR etc).
> > I
> > originally created an MX record to be the Static IP address of my router.
> > I
> > also created an A record to point remote.mydomain.co.uk to the same static
> > IP
> > address for OWA.
> >
> > Having done some more research into DNS / MX records I'm beginning to
> > think
> > that what i SHOULD have done is create an A record such as
> > mail.mydomain.co.uk and point it to my static IP, then create an MX record
> > pointing to mail.mydomain.co.uk.
>
> Either/or. I prefer domain names in MX records...one less thing to change
> and get cached if things have to get shuffled. I wouldn't call your setup
> *wrong* though, just not optimal.
>

> > As my mail is flowing I'm reluctant to make any changes. If I do need to
> > change it to what I mentioned above, can I do this without any emails
> > getting
> > bounced / lost?
>
> If you don't make any *wrong* changes then mail will flow just fine. Some
> DNS servers will have the old data cached, but since your IP isn't changing,
> it'll still get delivered. And new DNS queries will get the name and since
> that also appears to work, you'll continue to be fine. Should be
> transparent.
>

> > Final question, I've read a lot of PTR records being needed more and more.
> > On my control panel with Fasthosts all I can create are, A, Cname, MX,
> > AAAA
> > and TXT records. Will I need to contact Fasthosts and ask them to create a
> > PTR record for me? What do I need to have in this PTR? Sorry if that is a
> > dumb question but I'm just starting to learn this stuff.
>
> Not Fasthosts. Reverse lookups work backwards, so the PTR record would
> actually be owned/controlled by the owner of the IP address. In this case
> BT. Again, had you posted your public IP, we could have checked for you; it
> may already exist. It doesn't need to match your company, it need only
> exist.
>

> >
> > Kind regards,
> >
> > Chris
>
> .
>
 

My Computer

C

Cliff Galiher - MVP

#8
In regards to a backup service, let me say that SMTP as a protocol was
designed to handle delays. AFter all, if your server is down, even if you
have a backup service, the mail is delayed getting to YOU. So, in most
cases, I don't believe a backup service is necessary. Most mail servers
will attempt to resend every 4 hours, and your server should *not* be down
longer than that even during regular maintenance/patching/reboot. A good DR
plan is also essential for any server, and the max retry on most emails is
48 hours. You can get a new server rebuilt in that amount of time.

But for the paranoid and overly-cautious, there is always backup MX
services. I personally like DynDNS for the rare times I need to use one.
Inexpensive, easy to set up, and reliable.

-Cliff


"ChrisUK" <ChrisUK@newsgroup> wrote in message
news:2103E79E-0F66-4F15-A910-88B04BDD123D@newsgroup

> Cliff> OK - thanks for the heads up. My domain name registered with
> Fasthosts
> is www.zoo-hardware.co.uk. My internal domain name is zoohardware.local.
> Also, thanks for confirming that for me. I've made the change to the MX
> record from IP address (81.149.235.191) to mail.zoo-hardware.co.uk. I did
> this several hours ago and everything seems to be working.
>
> When I use nslookup to view a couple of other companyies who I know are
> using BT their MX records show as
> mail exchanger = host(ip-address).in-addr.btopenworld.com
>
> I was just concerned that mine appears much simpler.
>
> Also, i'd quite like a backup so if my server ever went down, mail would
> go
> somewhere else. I would obviously put that as a higher priority. I
> contacted
> Fasthosts about providing me with this facility but they didn't seem to
> offer
> that service (it might have been my limited understanding of what i was
> asking for!)
>
> Joe> I know what you mean with BT, they really don't appear to be very
> helpful on anything even slightly technical. I think i'll struggle to get
> them to do anything for me.
>
> Bill, Andrew and Ace> Thankyou for your input / help on this too!
>
>
>
> "Cliff Galiher - MVP" wrote:
>

>> Inline:
>>
>> -Cliff
>>
>>
>> "ChrisUK" <ChrisUK@newsgroup> wrote in message
>> news:EE6D581B-19F6-4A9C-ADED-98FD5B1288B2@newsgroup

>> > Hello,
>> >
>> > I am trying to get some clarification that my mx settings are OK. Mail
>> > is
>> > sending and receiving OK but I don't think its "by-the-book"
>> >
>> > I am running a SBS 2008 domain (lets call it mydomain.local) and I am
>> > hosting my own email server.
>> >
>> > I registered my domain name with fasthosts.co.uk (lets call it
>> > mydomain.co.uk).
>>
>> By not posting your real domain, you make it difficult for *us* to look
>> and
>> verify. And since it is a public domain, hackers are still going to find
>> and scan it. Obfuscating public domains in newsgroups provides *no*
>> added
>> security. Just for future reference.
>>

>> > I have a static IP address assigned by my ISP (BT - British Telecom)
>> > I have forwarded port 25 on my router to go to the internal IP address
>> > of
>> > my
>> > SBS. server
>> > On Fasthosts control panel I can set various DNS setting (A, mx, PTR
>> > etc).
>> > I
>> > originally created an MX record to be the Static IP address of my
>> > router.
>> > I
>> > also created an A record to point remote.mydomain.co.uk to the same
>> > static
>> > IP
>> > address for OWA.
>> >
>> > Having done some more research into DNS / MX records I'm beginning to
>> > think
>> > that what i SHOULD have done is create an A record such as
>> > mail.mydomain.co.uk and point it to my static IP, then create an MX
>> > record
>> > pointing to mail.mydomain.co.uk.
>>
>> Either/or. I prefer domain names in MX records...one less thing to
>> change
>> and get cached if things have to get shuffled. I wouldn't call your
>> setup
>> *wrong* though, just not optimal.
>>

>> > As my mail is flowing I'm reluctant to make any changes. If I do need
>> > to
>> > change it to what I mentioned above, can I do this without any emails
>> > getting
>> > bounced / lost?
>>
>> If you don't make any *wrong* changes then mail will flow just fine.
>> Some
>> DNS servers will have the old data cached, but since your IP isn't
>> changing,
>> it'll still get delivered. And new DNS queries will get the name and
>> since
>> that also appears to work, you'll continue to be fine. Should be
>> transparent.
>>

>> > Final question, I've read a lot of PTR records being needed more and
>> > more.
>> > On my control panel with Fasthosts all I can create are, A, Cname, MX,
>> > AAAA
>> > and TXT records. Will I need to contact Fasthosts and ask them to
>> > create a
>> > PTR record for me? What do I need to have in this PTR? Sorry if that is
>> > a
>> > dumb question but I'm just starting to learn this stuff.
>>
>> Not Fasthosts. Reverse lookups work backwards, so the PTR record would
>> actually be owned/controlled by the owner of the IP address. In this
>> case
>> BT. Again, had you posted your public IP, we could have checked for you;
>> it
>> may already exist. It doesn't need to match your company, it need only
>> exist.
>>

>> >
>> > Kind regards,
>> >
>> > Chris
>>
>> .
>>
 

My Computer

A

Andrew M. Saucci, Jr.

#9
In a hosted Exchange scenario, you may be given an MX on the hosting
company's domain, not your own. You're also sending from that mail server,
not your own. In that case, there would be no reason the HELO string
wouldn't match the rDNS of the hosting company's server.

Also, I've seen some pretty picky spam filters. We have a client
where two of the principals have personal AT&T mail accounts. They were
unable to send mail from the corporate domain to AT&T because the MX pointed
to an external spam filtering service and we were sending mail directly out,
making the source of the mail not match the MX. I think we solved that by
eliminating the spam filtering service and relying on Trend Micro Worry-Free
Business Security Advanced to handle it. AOL is also notorious for picky
spam filtering. Many mail server administrators are of the attitude that
fighting spam is a noble cause and if legitimate e-mail is filtered out in
the process, "too bad, you didn't set up your mail server right, or start
using a decent one like AT&T or AOL or MSN or Google."

Many legitimate scenarios are rejected by spam filters (or at least
result in higher scores); it's one of the things that drives me crazy about
e-mail and forces me to conclude that a major overhaul of Internet and
e-mail will eventually be demanded by end users.

The HELO is critical; I know that because SBS 2003 mangles it by
default (it defaults to domain.com, which is almost never right) and things
do not work right until I fix it, even if reverse DNS itself is correct.
Running the CEICW will usually break the HELO, and it must be fixed
maunally. Try it. Change the HELO on an otherwise properly configured
Exchange Server to "mail.fake.com" and try sending to AOL and see what
happens.

"Cliff Galiher - MVP" <cgaliher@newsgroup> wrote in message
news:etYJc6NlKHA.2592@newsgroup

> Just as a matter of debate, I've *never* seen a spam filter care if the
> reverse DNS *or* A record matches the HELO string in a mail server. In
> fact, more often than not, they don't.
>
> Take an example of a company that uses a cloud-based email service, such
> as an ISP server or hosted-Exchange. If you go the hosted-Exchange route,
> do you really think MS gives you your own Exchange servers and that the
> HELO strings match the MX/A record pair you set up? Or do you think that
> a service provider that offers businesses 10-20 free email accounts as
> part of their business bundle also gives them a dedicated server?
>
> There are so many *legitimate* scenarios where the HELO string will NOT
> match the MX record that no spam filters would rightfully reject or even
> negatively score messages that have a return header with such a setup.
>
> But what you say is true, a generic rDNS is usually perfectly adequate as
> long as the ISP also has an A record that matches the PTR record so that
> it is a matching pair. There isn't usually a cause to get them to create
> custom/renamed records.
>
> -Cliff
>
>
> "Andrew M. Saucci, Jr." <spam-only@newsgroup> wrote in message
> news:eyYMOLNlKHA.3476@newsgroup

>> Actually, the "generic" reverse DNS isn't nearly as much of a
>> problem as having none at all. If the ISP won't update the reverse DNS,
>> then setting up an A record to match it and changing the settings of the
>> SMTP virtual server to use that identity can work. It isn't pretty, but
>> it's legitimate. I don't think too many spam filters care much about what
>> your reverse DNS is as long as it matches what the SMTP server reports as
>> its identity in the HELO command. After all, the identity of a server in
>> the end is purely arbitrary.
>>
>> "Joe" <joe@newsgroup> wrote in message
>> news:%23LkxhPHlKHA.5128@newsgroup

>>> ChrisUK wrote:
>>>>
>>>> Final question, I've read a lot of PTR records being needed more and
>>>> more. On my control panel with Fasthosts all I can create are, A,
>>>> Cname, MX, AAAA and TXT records. Will I need to contact Fasthosts and
>>>> ask them to create a PTR record for me? What do I need to have in this
>>>> PTR? Sorry if that is a dumb question but I'm just starting to learn
>>>> this stuff.
>>>>
>>>
>>> You already know what to do, I'd add that I've known BT to be quite
>>> difficult about PTR records, even on 'business' accounts with static IP
>>> addresses. There will already be one of a generic kind, along the lines
>>> of 'adsl-12-34-56-67-pool.btconnect.com', but this is not likely to
>>> impress other mail servers. I have my own server configured to reject
>>> SMTP connections from addresses with PTR records of this kind.
>>>
>>> The bad news is that many mail servers, particularly those of ISPs, will
>>> expect a 'proper' PTR record of 'example.domain.com' form, and many
>>> (including mine) will expect there to be a valid A record for
>>> example.domain.com which points back to the IP address. I have not found
>>> it necessary for the PTR-A pair to match the MX record or HELO string,
>>> as mine do not and I have no problem sending mail to AOL, which is
>>> notoriously fussy.
>>>
>>> Certainly two or three years ago, BT wasn't good at organising this kind
>>> of thing. If they are still not willing to do it, then the only way you
>>> can send mail reliably is through another mail server which is
>>> considered 'respectable', such as an ISP's SMTP server. Check if your
>>> account with BT includes the use of an SMTP smarthost, as it is a
>>> facility you may want to use for other reasons.
>>>
>>> One of my customers insisted on using BT as ISP, against my
>>> recommendations, and took out a 'business' account. This turned out to
>>> have no smarthost facility and a fixed IP address that had a 'generic'
>>> PTR and was on a number of blacklists, none of which BT was prepared to
>>> do anything about. I ended up giving him an authenticated SMTP account
>>> on a web hosting package that I rent, to use as a smarthost. BT's
>>> recommendation, and I kid you not, was to use Yahoo for email. I think
>>> even today, BT subcontracts some parts of its email handling to Yahoo.
>>>
>>> --
>>> Joe
>>
>>
 

My Computer

A

Andrew M. Saucci, Jr.

#10
For someone who wants to try this without messing up a perfectly
good Exchange Server, an alternative is to use telnet to connect to AOL or
AT&T's mail server interactively. You can type anything you want after HELO;
it doesn't have to match what is programmed into SMTP (which would be
irrelevant).


"Andrew M. Saucci, Jr." <spam-only@newsgroup> wrote in message
news:uiHfYNYlKHA.5060@newsgroup

> Try it. Change the HELO on an otherwise properly configured Exchange
> Server to "mail.fake.com" and try sending to AOL and see what happens.
 

My Computer

C

ChrisUK

#11
Cliff> thanks again for the help.

Now I have posted my public IP, can you check to see if my PTR record is any
good?

Thanks again.

"Cliff Galiher - MVP" wrote:

> In regards to a backup service, let me say that SMTP as a protocol was
> designed to handle delays. AFter all, if your server is down, even if you
> have a backup service, the mail is delayed getting to YOU. So, in most
> cases, I don't believe a backup service is necessary. Most mail servers
> will attempt to resend every 4 hours, and your server should *not* be down
> longer than that even during regular maintenance/patching/reboot. A good DR
> plan is also essential for any server, and the max retry on most emails is
> 48 hours. You can get a new server rebuilt in that amount of time.
>
> But for the paranoid and overly-cautious, there is always backup MX
> services. I personally like DynDNS for the rare times I need to use one.
> Inexpensive, easy to set up, and reliable.
>
> -Cliff
>
>
> "ChrisUK" <ChrisUK@newsgroup> wrote in message
> news:2103E79E-0F66-4F15-A910-88B04BDD123D@newsgroup

> > Cliff> OK - thanks for the heads up. My domain name registered with
> > Fasthosts
> > is www.zoo-hardware.co.uk. My internal domain name is zoohardware.local.
> > Also, thanks for confirming that for me. I've made the change to the MX
> > record from IP address (81.149.235.191) to mail.zoo-hardware.co.uk. I did
> > this several hours ago and everything seems to be working.
> >
> > When I use nslookup to view a couple of other companyies who I know are
> > using BT their MX records show as
> > mail exchanger = host(ip-address).in-addr.btopenworld.com
> >
> > I was just concerned that mine appears much simpler.
> >
> > Also, i'd quite like a backup so if my server ever went down, mail would
> > go
> > somewhere else. I would obviously put that as a higher priority. I
> > contacted
> > Fasthosts about providing me with this facility but they didn't seem to
> > offer
> > that service (it might have been my limited understanding of what i was
> > asking for!)
> >
> > Joe> I know what you mean with BT, they really don't appear to be very
> > helpful on anything even slightly technical. I think i'll struggle to get
> > them to do anything for me.
> >
> > Bill, Andrew and Ace> Thankyou for your input / help on this too!
> >
> >
> >
> > "Cliff Galiher - MVP" wrote:
> >

> >> Inline:
> >>
> >> -Cliff
> >>
> >>
> >> "ChrisUK" <ChrisUK@newsgroup> wrote in message
> >> news:EE6D581B-19F6-4A9C-ADED-98FD5B1288B2@newsgroup
> >> > Hello,
> >> >
> >> > I am trying to get some clarification that my mx settings are OK. Mail
> >> > is
> >> > sending and receiving OK but I don't think its "by-the-book"
> >> >
> >> > I am running a SBS 2008 domain (lets call it mydomain.local) and I am
> >> > hosting my own email server.
> >> >
> >> > I registered my domain name with fasthosts.co.uk (lets call it
> >> > mydomain.co.uk).
> >>
> >> By not posting your real domain, you make it difficult for *us* to look
> >> and
> >> verify. And since it is a public domain, hackers are still going to find
> >> and scan it. Obfuscating public domains in newsgroups provides *no*
> >> added
> >> security. Just for future reference.
> >>
> >> > I have a static IP address assigned by my ISP (BT - British Telecom)
> >> > I have forwarded port 25 on my router to go to the internal IP address
> >> > of
> >> > my
> >> > SBS. server
> >> > On Fasthosts control panel I can set various DNS setting (A, mx, PTR
> >> > etc).
> >> > I
> >> > originally created an MX record to be the Static IP address of my
> >> > router.
> >> > I
> >> > also created an A record to point remote.mydomain.co.uk to the same
> >> > static
> >> > IP
> >> > address for OWA.
> >> >
> >> > Having done some more research into DNS / MX records I'm beginning to
> >> > think
> >> > that what i SHOULD have done is create an A record such as
> >> > mail.mydomain.co.uk and point it to my static IP, then create an MX
> >> > record
> >> > pointing to mail.mydomain.co.uk.
> >>
> >> Either/or. I prefer domain names in MX records...one less thing to
> >> change
> >> and get cached if things have to get shuffled. I wouldn't call your
> >> setup
> >> *wrong* though, just not optimal.
> >>
> >> > As my mail is flowing I'm reluctant to make any changes. If I do need
> >> > to
> >> > change it to what I mentioned above, can I do this without any emails
> >> > getting
> >> > bounced / lost?
> >>
> >> If you don't make any *wrong* changes then mail will flow just fine.
> >> Some
> >> DNS servers will have the old data cached, but since your IP isn't
> >> changing,
> >> it'll still get delivered. And new DNS queries will get the name and
> >> since
> >> that also appears to work, you'll continue to be fine. Should be
> >> transparent.
> >>
> >> > Final question, I've read a lot of PTR records being needed more and
> >> > more.
> >> > On my control panel with Fasthosts all I can create are, A, Cname, MX,
> >> > AAAA
> >> > and TXT records. Will I need to contact Fasthosts and ask them to
> >> > create a
> >> > PTR record for me? What do I need to have in this PTR? Sorry if that is
> >> > a
> >> > dumb question but I'm just starting to learn this stuff.
> >>
> >> Not Fasthosts. Reverse lookups work backwards, so the PTR record would
> >> actually be owned/controlled by the owner of the IP address. In this
> >> case
> >> BT. Again, had you posted your public IP, we could have checked for you;
> >> it
> >> may already exist. It doesn't need to match your company, it need only
> >> exist.
> >>
> >> >
> >> > Kind regards,
> >> >
> >> > Chris
> >>
> >> .
> >>
> .
>
 

My Computer

W

William

#12
On 15 Jan, 09:44, ChrisUK <Chri...@newsgroup> wrote:

> Now I have posted my public IP, can you check to see if my PTR record is any
> good?
Something is not right. I can Telnet to your IP-address and to your
FQDN on port 25, and both are responding correctly - but checks on
MXToolbox.com and on CheckDNS.net show that you do not have an MX
record, therefore no external mail can reach your server via SMTP.

http://www.mxtoolbox.com/SuperTool.aspx?action=mx:zoo-hardware.co.uk

http://www.checkdns.net/quickcheck.aspx?domain=zoo-hardware.co.uk+&detailed=1

I use the Fasthosts reseller package to host multiple domains, but I
find their DNS managament tools to be rather rudimentary. I prefer to
use www.zonedit.com for detailed DNS management. You can easily set up
a free package with them for up to 5 domains, and you just need to
repoint the DNS frtom Fasthosts.

--
WH
 

My Computer

#13
ChrisUK wrote:

> Cliff> thanks again for the help.
>
> Now I have posted my public IP, can you check to see if my PTR record is any
> good?
>
William has mentioned http://www.mxtoolbox.com which is (currently) free
and very useful for a variety of tests. There are many other free DNS
and mail testing sites, such as http://www.checkdns.net. There are sites
which will send you a test email or check for SMTP relaying.

You can make various SMTP tests yourself (such as whether an email
address is valid, or even send an email) using Telnet:

http://support.microsoft.com/kb/153119

Note that some mail servers require that sender and recipient email
addresses are enclosed in angle brackets <> and will return a syntax
error message if they're not. Normally, you'll need to test your own
server from outside the network, but that depends on your router and
your DNS setup.

Probably the quickest way to see your own PTR is to use http://grc.com
and locate the Shields Up!! test. Mr Gibson is a bit alarmist, so ignore
all the dire warnings. You're looking for: "The text below might
uniquely identify you on the Internet". This site is aimed at the home
user, and isn't as important as it was before XP SP2. It is still one of
the quickest ways to check for open ports.

--
Joe
 

My Computer

#14
Andrew M. Saucci, Jr. wrote:

> spam filtering. Many mail server administrators are of the attitude that
> fighting spam is a noble cause and if legitimate e-mail is filtered out in
> the process, "too bad, you didn't set up your mail server right, or start
> using a decent one like AT&T or AOL or MSN or Google."
I'm afraid I'm one of those. My mail server, supporting a small business
and a couple of humans, typically gets over 2000 bogus connections a
day. The large majority are NDR spams, which fail the 'valid recipient'
test, but I do need other techniques. If I do reject any valid email, I
do accept mail unconditionally to the abuse and postmaster addresses, as
required by RFC, and I've yet to see a single spam sent to either.

>
> Many legitimate scenarios are rejected by spam filters (or at least
> result in higher scores); it's one of the things that drives me crazy about
> e-mail and forces me to conclude that a major overhaul of Internet and
> e-mail will eventually be demanded by end users.
I've tried SpamAssassin, and my email client uses it, but I'm not keen
on content evaluation. I do (attempt to) run a business, so I can't use
a whitelist and it would be too easy to lose leads using content
filtering. I'd have no choice but to look at the failures, which rather
defeats the object... unless I can make sure there are only a handful a
day by using other methods.

>
> The HELO is critical; I know that because SBS 2003 mangles it by
> default (it defaults to domain.com, which is almost never right) and things
> do not work right until I fix it, even if reverse DNS itself is correct.
> Running the CEICW will usually break the HELO, and it must be fixed
> maunally. Try it. Change the HELO on an otherwise properly configured
> Exchange Server to "mail.fake.com" and try sending to AOL and see what
> happens.
>
I check that a HELO can be found in public DNS, and go no further. A
domain name is OK, it doesn't have to be a hostname. I don't think many
servers go further than this: when I make a telnet connection to a mail
server for test purposes, I usually use a well-known six-character
domain name rather than type in a hostname that I own, and I've never
had a problem.

--
Joe
 

My Computer

C

Cliff Galiher - MVP

#15
Others have given you good advice on good self-test tools (I prefer
MXToolbox) but yes, your PTR record is set by your ISP and they have a
matching A record as well. Should be good to go on that front.

-Cliff


"ChrisUK" <ChrisUK@newsgroup> wrote in message
news:987D3565-3435-4C00-94A7-23BE003C9CEC@newsgroup

> Cliff> thanks again for the help.
>
> Now I have posted my public IP, can you check to see if my PTR record is
> any
> good?
>
> Thanks again.
>
> "Cliff Galiher - MVP" wrote:
>

>> In regards to a backup service, let me say that SMTP as a protocol was
>> designed to handle delays. AFter all, if your server is down, even if
>> you
>> have a backup service, the mail is delayed getting to YOU. So, in most
>> cases, I don't believe a backup service is necessary. Most mail servers
>> will attempt to resend every 4 hours, and your server should *not* be
>> down
>> longer than that even during regular maintenance/patching/reboot. A good
>> DR
>> plan is also essential for any server, and the max retry on most emails
>> is
>> 48 hours. You can get a new server rebuilt in that amount of time.
>>
>> But for the paranoid and overly-cautious, there is always backup MX
>> services. I personally like DynDNS for the rare times I need to use one.
>> Inexpensive, easy to set up, and reliable.
>>
>> -Cliff
>>
>>
>> "ChrisUK" <ChrisUK@newsgroup> wrote in message
>> news:2103E79E-0F66-4F15-A910-88B04BDD123D@newsgroup

>> > Cliff> OK - thanks for the heads up. My domain name registered with
>> > Fasthosts
>> > is www.zoo-hardware.co.uk. My internal domain name is
>> > zoohardware.local.
>> > Also, thanks for confirming that for me. I've made the change to the MX
>> > record from IP address (81.149.235.191) to mail.zoo-hardware.co.uk. I
>> > did
>> > this several hours ago and everything seems to be working.
>> >
>> > When I use nslookup to view a couple of other companyies who I know are
>> > using BT their MX records show as
>> > mail exchanger = host(ip-address).in-addr.btopenworld.com
>> >
>> > I was just concerned that mine appears much simpler.
>> >
>> > Also, i'd quite like a backup so if my server ever went down, mail
>> > would
>> > go
>> > somewhere else. I would obviously put that as a higher priority. I
>> > contacted
>> > Fasthosts about providing me with this facility but they didn't seem to
>> > offer
>> > that service (it might have been my limited understanding of what i was
>> > asking for!)
>> >
>> > Joe> I know what you mean with BT, they really don't appear to be very
>> > helpful on anything even slightly technical. I think i'll struggle to
>> > get
>> > them to do anything for me.
>> >
>> > Bill, Andrew and Ace> Thankyou for your input / help on this too!
>> >
>> >
>> >
>> > "Cliff Galiher - MVP" wrote:
>> >
>> >> Inline:
>> >>
>> >> -Cliff
>> >>
>> >>
>> >> "ChrisUK" <ChrisUK@newsgroup> wrote in message
>> >> news:EE6D581B-19F6-4A9C-ADED-98FD5B1288B2@newsgroup
>> >> > Hello,
>> >> >
>> >> > I am trying to get some clarification that my mx settings are OK.
>> >> > Mail
>> >> > is
>> >> > sending and receiving OK but I don't think its "by-the-book"
>> >> >
>> >> > I am running a SBS 2008 domain (lets call it mydomain.local) and I
>> >> > am
>> >> > hosting my own email server.
>> >> >
>> >> > I registered my domain name with fasthosts.co.uk (lets call it
>> >> > mydomain.co.uk).
>> >>
>> >> By not posting your real domain, you make it difficult for *us* to
>> >> look
>> >> and
>> >> verify. And since it is a public domain, hackers are still going to
>> >> find
>> >> and scan it. Obfuscating public domains in newsgroups provides *no*
>> >> added
>> >> security. Just for future reference.
>> >>
>> >> > I have a static IP address assigned by my ISP (BT - British Telecom)
>> >> > I have forwarded port 25 on my router to go to the internal IP
>> >> > address
>> >> > of
>> >> > my
>> >> > SBS. server
>> >> > On Fasthosts control panel I can set various DNS setting (A, mx, PTR
>> >> > etc).
>> >> > I
>> >> > originally created an MX record to be the Static IP address of my
>> >> > router.
>> >> > I
>> >> > also created an A record to point remote.mydomain.co.uk to the same
>> >> > static
>> >> > IP
>> >> > address for OWA.
>> >> >
>> >> > Having done some more research into DNS / MX records I'm beginning
>> >> > to
>> >> > think
>> >> > that what i SHOULD have done is create an A record such as
>> >> > mail.mydomain.co.uk and point it to my static IP, then create an MX
>> >> > record
>> >> > pointing to mail.mydomain.co.uk.
>> >>
>> >> Either/or. I prefer domain names in MX records...one less thing to
>> >> change
>> >> and get cached if things have to get shuffled. I wouldn't call your
>> >> setup
>> >> *wrong* though, just not optimal.
>> >>
>> >> > As my mail is flowing I'm reluctant to make any changes. If I do
>> >> > need
>> >> > to
>> >> > change it to what I mentioned above, can I do this without any
>> >> > emails
>> >> > getting
>> >> > bounced / lost?
>> >>
>> >> If you don't make any *wrong* changes then mail will flow just fine.
>> >> Some
>> >> DNS servers will have the old data cached, but since your IP isn't
>> >> changing,
>> >> it'll still get delivered. And new DNS queries will get the name and
>> >> since
>> >> that also appears to work, you'll continue to be fine. Should be
>> >> transparent.
>> >>
>> >> > Final question, I've read a lot of PTR records being needed more and
>> >> > more.
>> >> > On my control panel with Fasthosts all I can create are, A, Cname,
>> >> > MX,
>> >> > AAAA
>> >> > and TXT records. Will I need to contact Fasthosts and ask them to
>> >> > create a
>> >> > PTR record for me? What do I need to have in this PTR? Sorry if that
>> >> > is
>> >> > a
>> >> > dumb question but I'm just starting to learn this stuff.
>> >>
>> >> Not Fasthosts. Reverse lookups work backwards, so the PTR record
>> >> would
>> >> actually be owned/controlled by the owner of the IP address. In this
>> >> case
>> >> BT. Again, had you posted your public IP, we could have checked for
>> >> you;
>> >> it
>> >> may already exist. It doesn't need to match your company, it need
>> >> only
>> >> exist.
>> >>
>> >> >
>> >> > Kind regards,
>> >> >
>> >> > Chris
>> >>
>> >> .
>> >>
>> .
>>
 

My Computer

A

Andrew M. Saucci, Jr.

#16
Actually, I just took myself up on my own challenge. I opened a
Telnet connection to AOL's mail server and manually sent an e-mail using a
HELO of mail.fake.com. I was surprised to see that it actually went through,
but it did get put into the spam folder, which in most cases is as good as
if it had been rejected outright. Perhaps HELO isn't as important as I had
thought, but every time it's wrong clients start complaining that their mail
isn't going through, so I would still be sure it matches the reverse DNS.

"Andrew M. Saucci, Jr." <spam-only@newsgroup> wrote in message
news:uiHfYNYlKHA.5060@newsgroup

> In a hosted Exchange scenario, you may be given an MX on the
> hosting company's domain, not your own. You're also sending from that mail
> server, not your own. In that case, there would be no reason the HELO
> string wouldn't match the rDNS of the hosting company's server.
>
> Also, I've seen some pretty picky spam filters. We have a client
> where two of the principals have personal AT&T mail accounts. They were
> unable to send mail from the corporate domain to AT&T because the MX
> pointed to an external spam filtering service and we were sending mail
> directly out, making the source of the mail not match the MX. I think we
> solved that by eliminating the spam filtering service and relying on Trend
> Micro Worry-Free Business Security Advanced to handle it. AOL is also
> notorious for picky spam filtering. Many mail server administrators are of
> the attitude that fighting spam is a noble cause and if legitimate e-mail
> is filtered out in the process, "too bad, you didn't set up your mail
> server right, or start using a decent one like AT&T or AOL or MSN or
> Google."
>
> Many legitimate scenarios are rejected by spam filters (or at least
> result in higher scores); it's one of the things that drives me crazy
> about e-mail and forces me to conclude that a major overhaul of Internet
> and e-mail will eventually be demanded by end users.
>
> The HELO is critical; I know that because SBS 2003 mangles it by
> default (it defaults to domain.com, which is almost never right) and
> things do not work right until I fix it, even if reverse DNS itself is
> correct. Running the CEICW will usually break the HELO, and it must be
> fixed maunally. Try it. Change the HELO on an otherwise properly
> configured Exchange Server to "mail.fake.com" and try sending to AOL and
> see what happens.
>
> "Cliff Galiher - MVP" <cgaliher@newsgroup> wrote in message
> news:etYJc6NlKHA.2592@newsgroup

>> Just as a matter of debate, I've *never* seen a spam filter care if the
>> reverse DNS *or* A record matches the HELO string in a mail server. In
>> fact, more often than not, they don't.
>>
>> Take an example of a company that uses a cloud-based email service, such
>> as an ISP server or hosted-Exchange. If you go the hosted-Exchange
>> route, do you really think MS gives you your own Exchange servers and
>> that the HELO strings match the MX/A record pair you set up? Or do you
>> think that a service provider that offers businesses 10-20 free email
>> accounts as part of their business bundle also gives them a dedicated
>> server?
>>
>> There are so many *legitimate* scenarios where the HELO string will NOT
>> match the MX record that no spam filters would rightfully reject or even
>> negatively score messages that have a return header with such a setup.
>>
>> But what you say is true, a generic rDNS is usually perfectly adequate as
>> long as the ISP also has an A record that matches the PTR record so that
>> it is a matching pair. There isn't usually a cause to get them to create
>> custom/renamed records.
>>
>> -Cliff
>>
>>
>> "Andrew M. Saucci, Jr." <spam-only@newsgroup> wrote in message
>> news:eyYMOLNlKHA.3476@newsgroup

>>> Actually, the "generic" reverse DNS isn't nearly as much of a
>>> problem as having none at all. If the ISP won't update the reverse DNS,
>>> then setting up an A record to match it and changing the settings of the
>>> SMTP virtual server to use that identity can work. It isn't pretty, but
>>> it's legitimate. I don't think too many spam filters care much about
>>> what your reverse DNS is as long as it matches what the SMTP server
>>> reports as its identity in the HELO command. After all, the identity of
>>> a server in the end is purely arbitrary.
>>>
>>> "Joe" <joe@newsgroup> wrote in message
>>> news:%23LkxhPHlKHA.5128@newsgroup
>>>> ChrisUK wrote:
>>>>>
>>>>> Final question, I've read a lot of PTR records being needed more and
>>>>> more. On my control panel with Fasthosts all I can create are, A,
>>>>> Cname, MX, AAAA and TXT records. Will I need to contact Fasthosts and
>>>>> ask them to create a PTR record for me? What do I need to have in this
>>>>> PTR? Sorry if that is a dumb question but I'm just starting to learn
>>>>> this stuff.
>>>>>
>>>>
>>>> You already know what to do, I'd add that I've known BT to be quite
>>>> difficult about PTR records, even on 'business' accounts with static IP
>>>> addresses. There will already be one of a generic kind, along the lines
>>>> of 'adsl-12-34-56-67-pool.btconnect.com', but this is not likely to
>>>> impress other mail servers. I have my own server configured to reject
>>>> SMTP connections from addresses with PTR records of this kind.
>>>>
>>>> The bad news is that many mail servers, particularly those of ISPs,
>>>> will expect a 'proper' PTR record of 'example.domain.com' form, and
>>>> many (including mine) will expect there to be a valid A record for
>>>> example.domain.com which points back to the IP address. I have not
>>>> found it necessary for the PTR-A pair to match the MX record or HELO
>>>> string, as mine do not and I have no problem sending mail to AOL, which
>>>> is notoriously fussy.
>>>>
>>>> Certainly two or three years ago, BT wasn't good at organising this
>>>> kind of thing. If they are still not willing to do it, then the only
>>>> way you can send mail reliably is through another mail server which is
>>>> considered 'respectable', such as an ISP's SMTP server. Check if your
>>>> account with BT includes the use of an SMTP smarthost, as it is a
>>>> facility you may want to use for other reasons.
>>>>
>>>> One of my customers insisted on using BT as ISP, against my
>>>> recommendations, and took out a 'business' account. This turned out to
>>>> have no smarthost facility and a fixed IP address that had a 'generic'
>>>> PTR and was on a number of blacklists, none of which BT was prepared to
>>>> do anything about. I ended up giving him an authenticated SMTP account
>>>> on a web hosting package that I rent, to use as a smarthost. BT's
>>>> recommendation, and I kid you not, was to use Yahoo for email. I think
>>>> even today, BT subcontracts some parts of its email handling to Yahoo.
>>>>
>>>> --
>>>> Joe
>>>
>>>
>
>
 

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