By default on the Messaging Server, users need not submit a password when they connect to the SMTP service of the Messaging Server to send a message. (We do not force SMTP AUTH.)
Authenticated SMTP is an extension to the SMTP protocol that allows clients to authenticate to the server. The authentication accompanies the message. The primary use of authenticated SMTP is to allow local users who are traveling (or using their home ISP) to submit mail (relay mail) without creating an open relay that others can abuse. The AUTH command is used by the client to authenticate to the server.
You can use authenticated SMTP with or without SSL encryption.
The maysaslserver, mustsaslserver, nosasl, nosaslserver, switchchannel, and saslswitchchannel ...