PMDF-TLS implements the TLS protocol (Transport Layer Security; see RFC 2246) for PMDF's servers and clients. Transport Layer Security is currently supported for:

• SMTP (server and client),
• IMAP,
• POP3, and
• HTTP.

PMDF-TLS provides for a secure data stream between the client and the server so that users can ensure that the data that is exchanged between their system and a remote system using TLS will be protected from others on the network.

Note that TLS is backwards compatible with SSL (Secure Sockets Layer) and PMDF-TLS is fully compatible with SSL-enabled clients. Because TLS includes all necessary SSL functionality, this document will refer to TLS exclusively.