An email server is server software which accepts email for one or more recipients and stores it until deleted by an email client (usually as part of the delivery process). The term "email server" may refer to the software, the hardware on which the software runs, or the combination of the two.
In order for a minimal email server to function, the following must happen:
- The hardware must have MTA (to receive email) and MDA (for clients to pick up the mail) server software installed and working
- The domain(s) for which the server is expected to handle email must have at least one MX record pointing to the server's IP address or hostname (otherwise nobody else will know how to deliver email sent to those domains)
- If the server is behind a firewall, that firewall must be configured:
The tricky part of configuring the server appears to be the account names and aliases; these can be configured via a baffling array of standards which I have not yet figured out. The "easy way" seems to be to configure it via a control panel such as Webmin.
- MTA: Mail Transfer Agent or Mail Transport Agent - sends and receives email to and from other servers on the Internet (usually via SMTP)
- MDA: Mail Delivery Agent - hold emails for delivery to users (usually via POP3 or IMAP)
- POP3: the current version of the Post Office Protocol which allows an email client to retrieve mail from a server
- IMAP: Internet Mail Access Protocol
- SMTP: Simple Mail Transfer Protocol
These packages include both the MTA and MDA.
For now, a collection of links:
- 2009-06-11 How to set up a (Postfix) mail server on a GNU / Linux system "Based on an Ubuntu distribution platform, but instructions are distro generic."
- 2004-12-15 Email Server Setup: a 5-page article