Are you trying to access it from the local network or from outside the local network?
By default, SME 7 only allows pop3 or imap access from the local network. From any other network, you have to change "Configuration", "Email", "POP3 Server Access" and "IMAP server access" from "Allow Private" to "Allow private and public secure (POP3S)" and "Allow private and public secure (IMAPS)".
Once you've selected "Allow private and public...", you have to setup your client to use Secure POP3 on port 995 or IMAPS on port 993. You may have to do this even from the local network once you've selected the "private and public" option...