Mail server

A mail server (hereinafter, the Server) is any software instance that transfers electronic mail messages from one computer to another using the Simple Mail Transfer Protocol (SMTP). Usually, the Servers use other protocols such as POP3 and IMAP to communicate with mail user agents (or MUAs), which end-users usually utilize.

The Server can also refer to mail server software or, more broadly, to email software used to setup the Server.

Categories

The Server may be one of the following four:

1. Mail submission agent (also known as outgoing mail server, message submission agent or by its acronym MSA);
2. Mail transfer agent (also known as message transfer agent or by its acronym MTA);
3. Mail exchanger (also known as mail relay, message exchanger or MX, and MX host);
4. Mail delivery agent (also known as incoming mail server, message delivery agent or by its acronym MDA).

Common senders submit their electronic mail messages to their MUA, which transfers the message to the mail submission agent, which transfers the message to either mail delivery agent or mail exchanger between the two. Finally, the mail delivery agent transfers the message to receiver's MUA.

Best practices

• https://skrilnetz.net/setup-your-own-mailserver/
• https://www.linuxbabe.com/mail-server/block-email-spam-postfix
• https://manuals.gfi.com/en/kerio/connect/content/server-configuration/mail-delivery-and-dns-records/essential-dns-records-for-mail-delivery-and-spam-protection-1223.html
• https://www.cyberpunk.rs/mail-server-setup-postfix