18.104.22.168 Email Servers
Email has always been a widespread use for Linux servers. When discussing email servers, it is always helpful to look at the 3 different tasks required to get email between people:
- Mail Transfer Agent (MTA)The most well known MTA (software that is used to transfer electronic messages to other systems) is Sendmail. Postfix is another popular one and aims to be simpler and more secure than Sendmail.
- Mail Delivery Agent (MDA)Also called the Local Delivery Agent, it takes care of storing the email in the user’s mailbox. Usually invoked from the final MTA in the chain.
- POP/IMAP ServerThe Post Office Protocol (POP) and Internet Message Access Protocol (IMAP) are two communication protocols that let an email client running on your computer talk to a remote server to pick up the email.
Dovecot is a popular POP/IMAP server owing to its ease of use and low maintenance. Cyrus IMAP is another option. Some POP/IMAP servers implement their own mail database format for performance and include the MDA if the custom database is desired. People using standard file formats (such as all the emails in one text file) can choose any MDA.
There are several significant differences between the closed source and open source software worlds, one being that of inclusion of other projects as components to a project or package.In the closed source world, Microsoft Exchange is shipped primarily as a software package/suite that includes all the necessary or approved components, all from Microsoft, so there are few if any options to make individual selections. In the open source world, many options can be modularly included or swapped out for package components, and indeed some software packages or suites are just a well-packaged set of otherwise individual components all harmoniously working together.