You should have something like this:

[MailScanner]
DefaultPopServer=mail.securenet.net
DefaultSmtpServer=pop.securenet.net
ShowTrayIcon=1
UseDefaultSmtp=0
AutoSetProtection=0
PopListen=127.0.0.1:110
SmtpListen=127.0.0.1:25
ImapListen=127.0.0.1:143

Of course with your mail pop3 and smtp server names instead of those listed up there…