Mail Submission Agent

A Message Submission Agent (MSA ) is a server that sends e - mails from a mail user agent and receives a Mail Delivery Agent or Mail Transfer Agent passes.

Traditionally accept mail transfer agents such e -mails. While Mail Transfer Agents are reachable on port 25 is provided for Message Submission Agents of port 587.

Because mail transfer agents were originally designed for communication among themselves, grew with the increase einliefernder Mail User Agents the problem spam. Mail User Agents are not verifiable using Domain Name System, so that it can be switched for them to query a user name and password. First it was the detour SMTP - after- POP, and then pushed SMTP Auth one. By Message Submission Agent Mail Transfer Agents can be relieved of it again. The two servers can be tailored to their particular task.

The Extended Simple Mail Transfer Protocol is a mandatory basis for Message Submission Agents.