Messaging Server supports encrypted communications with IMAP, POP and HTTP clients by using the Secure Sockets Layer (SSL) protocol. For general information on support for SSL in Messaging Server, see 23.5 Configuring Encryption and Certificate-Based Authentication.
You can accept the default (recommended) IMAP over SSL port number (993) or you can specify a different port for IMAP over SSL.
Messaging Server provides the option of using separate ports for IMAP and IMAP over SSL because most current IMAP clients require separate ports for them. Same-port communication with both IMAP and IMAP over SSL is an emerging standard; as long as your Messaging Server has an installed SSL certificate (see 23.5.1 Obtaining Certificates), it can support same-port IMAP over SSL.
The default separate SSL port for POP is 995. One can also initiate SSL over normal POP port with the command “STLS” (see 5.5 To Configure POP Services).
You can accept the default HTTP over SSL port number (443) or you can specify a different port for HTTPS.