pF> I'm planning to move my BBS to a Linux VPS, and am unsure how to best
 pF> set up SMTP. I'd like to have Postfix running on port 25 on the box,
 pF> and have it deliver mail to local folders for shell users. Mail for
 pF> BBS users would stay in the BBS.

 pF> I was thinking I could have Postfix configured to answer on port 25,
 pF> set as MX for domain1.com (for shell users) and domain2.com (for BBS
 pF> users). I could use a transport map to route mail to domain2.com on an
 pF> alternate port for the BBS, and configure Synchronet's SMTP server to
 pF> use that port.

 pF> I'm not sure if I'm missing something here.

 pF> How do you handle mail in a similar situation?

Sounds good and I don't know any other way to do it, if you have one IP address
only. Postfix is the relay server for domain2 (relay_domains) and forwards
mails to Synchronet.