POP3 as a protocol was never meant to be used between servers. Many ISPs
won't let you query a server much more often than that because of the
network overhead it incurs and, along with some security concerns (passwords
are sent in clear text by default, for example), querying too often can get
your ISP to lock you out, slow down your server if there are multiple
mailboxes, and increases the chance that someone can sniff out your ISP
If you want faster email delivery, look at moving to SMTP. The pop3
connector is a tool to help new SBS installations migrate from ISP-stored
emails to in-house email, but should not be used as a long-term solution.
Is it possible - yes, IIRC, there is a registry hack to reduce the interval
to less than 15 minutes. Is it advisable - probably not. If the POP3
Manager is downloading mail when another POP3 download event is triggered,
there is a potential for things to go pear-shaped. That said, there are
also 3rd party POP3 retrieval products that will allow you to set the
interval to less than 15 minutes.
.... plus, what Cliff said about lock outs from your ISP.