Vista - Can't send mail through POP3 account

I'm working for a new company and am trying to set up my POP3 through Windows
mail. The incoming and outgoing servers are the same (mail.companyname.com).

I am able to receive email from this account. When I try to send an email I
get an error message:

The connection to the server has failed. Subject 'Test', Account:
'mail.brennco.com', Server: 'mail.brennco.com', Protocol: SMTP, Port: 25,
Secure(SSL): No, Socket Error: 10060, Error Number: 0x800CCC0E

My company has tested my incoming/outgoing email at their end and say it is
fine. I called my ISP (ATT) and the can not support anything other than ATT
mail.

Can anyone assist - I really need to get this working!

Thanks

"mexigrl" <mexigrl@xxxxxx> wrote in message
news:42715EFD-E4D1-4A48-99E7-B8A3EAB890C3@xxxxxxMany internet providers block connections to port 25 on mail servers other
than their own, to cause problems for spammers. You might ask the company
if their mail server listens for outgoing mail on any port other than port
25,
and if so, the details of how to switch to the other port. Just trying all
the
ports is a very slow way of finding this information; there are about 65,000
ports available.

You could also check if your part of AT&T listens for outgoing mail on
any port other than port 25, and if so, switch to using their outgoing mail
server all the time even if you keep using the same incoming mail server
and the same return address as before.

http://helpme.att.net/article.php?item=10918