Yes, I do use SSL, so its port 993 that is used. I tested this by adding ImapListen=127.0.0.1:993 to the ini file, but when I reconfigure mozilla and try to access mail, mozilla shows 'connecting to 127.0.0.1' after a while, an avast dialog box pops up with 'Internet connection timed out. Continue waiting?'
The Mail scanner does not support SSL, so it will not work even if you change the port to 993.
With the mail scanner running, I scanned the open ports and none of the 3 ports above were open. I'm guessing this isnt an issue as the pop3 and smtp mail scanning works fine. If i do have to open a port, I'm not quite sure how to do it.
If the pop3 and smtp mail scanning works then I think it's not a problem. Your port monitor probably detects the ports not precisely as closed.