VB_For_Dummies, if I understand your correctly, you have a SMTP server on the same computer as Avast and you experience problems when some programs (especialy phpForum via Apache) are trying to send mails from this PC.

You cannot run more than one program listening on the same TCP port. In this situation both your SMTP server and Avast Mail Scanner are fighting for control of port 25. The one which starts first gets it and other one could not function properly.

You have to change the configuration of one of them. The simpliest thing would be to move avast Mail Scan to an other port (say 2525). Mail clients will then connect directly to your SMTP server listening on 127.0.0.1:25. SMTP Server will accept the mail from client and will try to deliver it to its destination (other PC in the internet). At that time automatic SMTP scanner (new in version 4.5) will intercept the connection and scan the mail for viruses. (by forwarding it to the port 2525 where avast! mail scanner is listening).

You may change the port where avast! SMTP Scanner is listening by editing the file Avast4\DATA\avast4.ini, the section

[MailScanner]
SmtpListen=127.0.0.1:2525

Hope it helps, I am not really sure If got to the nature of your problem.
Cheers Lukas.

BTW: Beware when opening a SMTP server on your PC accessible from the internet. When not configured properly it may soon be found by some SPAM ‘lovers’ and ab-used to spread SPAM. But at least (with avast! Internet Mail scan) they might get their spams checked for viruses . :stuck_out_tongue: