Mail Submission Agent

A Message Submission Agent (MSA) is a server that receives mail from a Mail User Agent and delivers it to a Mail Delivery Agent or Mail Transfer Agent.

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

Because mail transfer agents were originally designed for communication among themselves, the problem of spam increased with the increase in incoming mail user agents. Mail user agents can not be verified by means of a domain name system, so that they must be switched over to a query of user name and password. First you went the detour SMTP-after-POP and then inserted SMTP-Auth. With Message Submission Agents, Mail Transfer Agents can be relieved. The two servers can be tailored exactly to their respective tasks.

The Extended Simple Mail Transfer Protocol is mandatory for Message Submission Agents. Weblinks Edit sourcetext

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