Finally, you can also dedicate specific ports for SSL connections. This isn't required but can provide a further level of accessibility for clients that do not support certain SSL extensions. For example, some versions of Microsoft Outlook Express don't support STARTTLS for IMAP over the default mail port, but do support connections to dedicated SSL ports.
The options for enabling and configuring SSL are located under the SSL & TLS section of the Security Settings dialog at: Security » Security Settings » SSL & TLS. The SSL port settings for SMTP, POP3, and IMAP are located on the Ports screen at: Setup » Server Settings.
For information on creating and using SSL Certificates, see:
Creating & Using SSL Certificates
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The TLS/SSL protocol is addressed in RFC-2246, which can be viewed at:
http://www.rfc-editor.org/rfc/rfc2246.txt
The STARTTLS extension for SMTP is addressed in RFC-3207, which can be viewed at:
http://www.rfc-editor.org/rfc/rfc3207.txt
Using TLS with the IMAP and POP3 protocols is addressed in RFC-2595, which can be viewed at: