On a network like the internet, mail clients send mail to a mail server which then routes the messages to the correct destinations (other clients). the mail server uses a network application called a mail transfer agent (mta).
What is a Mail Transfer Agent (MTA)?
An mta is an application that routes and transmits email from one node of a network to another. uses a protocol known as smtp (Simple Mail Transfer Protocol) to accomplish its task.
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On a network node, there is an email client that is used to send and receive messages to and from the mail server, an email client also uses the smtp protocol but is not necessarily an mta .
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mta are installed on a mail server and email clients such as mozilla thunderbird, evolution, microsoft’s outlook, and apple mail are installed on a mail client (user’s computer).
In this article, we will see a summary of the best and most used mta in linux mail servers.
1. send mail
sendmail now known as proofpoint (after proofpoint, inc acquired sendmail, inc) is by far the most popular and one of the oldest mta’s in the linux server platform. however, sendmail has many limitations compared to modern mtas.
Because of its complicated configuration steps and demands, and its weak security mechanisms, many new mtas have emerged as alternatives to sendmail, but more importantly, it offers everything that has to do with mail over a network.
visit home page: http://www.sendmail.com
2. postfix
postfix is a popular cross-platform mta that was designed and developed by wietse zweitze venema for his mail server while working in the research department of ibm.
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It was mainly developed as an alternative to the well-known and popular sendmail mta. postfix runs on linux, mac osx, solaris, and several other unix-like operating systems.
borrows many sendmail properties from the outside, but has a completely different internal operation. In addition, it offers fast performance with easy settings and a safe operation mechanism, and has the following main features:
- spam control
- multi-protocol support
- database support
- mailbox support
- address manipulation support and much more
visit home page: http://www.postfix.org
3. exempt
exim is a free mta developed for unix-like operating systems like linux, mac osx, solaris and many more. exim offers a great level of flexibility in routing mail on a network, with excellent mechanisms and facilities for monitoring incoming mail.
Notable features include, but are not limited to:
- does not support pop and imap protocols
- supports protocols such as rfc 2821 smtp and rfc 2033 lmtp email message transport
- configurations include access control lists , content scanning, encryption, routing controls, among others
- excellent documentation
- has utilities like lemonade, which is a variety of smtp and imap extensions to enable mobile messaging and many more.
visit home page: http://www.exim.org/
4. qmail
qmail is also another free and open source modern linux mta compared to the other mta’s we have seen. furthermore, it is simple, reliable, efficient, and offers extensive security features, thus a secure mta package.
It is relatively small but feature rich and some of its features include:
- runs on various unix-like operating systems such as freebsd, solaris, mac osx and many more
- simple and fast installation
- automatic configuration per host
- clear separation between addresses, files and programs
- full support for groups of addresses
- allows each user to manage their own mailing lists
- supports an easy way to set up a mailing list
- supports verps
- supports automatic mailing list loop prevention
- supports mailing list manager ezmlm mail
- random lists not supported and many more
visit home page: http://cr.yp.to/qmail.html
5. mutt – command line email client
mutt is a small but powerful terminal-based email client for unix-like operating systems. has some cool features as a text based email client, and some of its notable features include:
- message chaining
- support for imap and pop3 protocols
- supports various mailbox formats such as mbox, mh, maildir, mmdf
- delivery status support
- multiple message tagging
- pgp/mime (rfc2015) support
- several features to support the mailing list, including replying to the list
- full control of message headers during composing
- easy to install
- active development community and much more
visit home page: http://www.mutt.org/
6. alpine
alpine is a fast and easy to use terminal based email client for linux, it is based on the pine messaging system. works well for both beginners and advanced users, users can easily learn how to use it through context sensitive help.
more importantly, it is highly customizable via alpine’s config command.
visit home page: https://www.washington.edu/alpine/
7. open mtp
opensmtpd is an open source mail transfer agent used to deliver messages on a local system or to relay them to other smtp servers. It also comes with a web service that allows emails to be sent through an http web server. runs on various unix and unix-like operating systems, such as linux, freebsd, openbsd, netbsd, and osx.
In this overview, we’ve seen a brief introduction to how mail is routed and transmitted over a network from mail clients to mail servers, and more importantly, a little understanding of how mtas work and a list of the best and most used linux. mta that you probably want to install to create a mail server.
There are several other mtas, but they all have advantages and limitations like the ones we’ve reviewed here.