Pete, send an IM to Culpeper. He knows everything about SpamPal.
Regarding the changes needed for SpamPal, you can configure your email account manually. Your configuration must be:
SMTP server: 127.0.0.1
POP server: 127.0.0.1
account login: user name#isp name
Note: # and not @
smtp authentication on
user id: #smtp_address
password: blank or yours
Check to remember the password
Note: user id without user name
And into avast4.ini file at section [MailScanner]:
DefaultSmtpServer=127.0.0.1:25
DefaultPopServer=127.0.0.1:110
SmtpListen=127.0.0.1:25
PopListen=127.0.0.1:110
ImapListen=127.0.0.1:143
More information about the avast4.ini file you can see here and probably you will be able to solve the problem at port 143.