email has proven to be the fastest and most reliable means of communication of our time. From businesses to individuals, we all rely on emails because of the convenience they offer. If you’ve ever wondered how computers send these seemingly simple messages over the network, follow us through this guide. There are mainly two software components at the heart of email communication, namely the mail server and the mail client. The mail server is responsible for transmitting email from node to node on a network, usually the Internet. and the client allows users to retrieve these emails. in this guide, we will only focus on the linux mail server. see another guide for more information on various linux mail clients.
first level linux mail server
Like many other departments of software, Linux offers some of the best mail transfer agents (mta). Our editors have gone through a great selection of these tools and selected the 20 best Linux mail servers for you. these include open source and proprietary mail servers. stay with us for more detailed information about various linux email servers.
1. exempt
exim is a feature-rich mail server used on many unix-like operating systems, such as linux and bsd. it also provides efficient cross-platform support, making it a perfect choice for mail servers that need to be diverse and handle a large number of requests.
Being written entirely in c, exim offers excellent performance and works very well even on legacy systems. In addition, the development team implements frequent updates and takes good care of bug fixes.
exim characteristics
- exim is arguably among the best mail transfer agents when it comes to customization and configuration capabilities.
- features three different logging mechanisms to prevent email spam, a namely, the main log, the emergency log, and the reject log.
- exim comes with built-in support for a wide range of database management systems such as mysql, postgresql, sqlite, oracle db, and redis.
- gnu gpl license presented by this linux mail server allows administrators to freely modify the software according to their requirements.
download exim
2. postfix
postfix is an immensely powerful open source mail server that can be used to route and deliver email. offers a robust set of useful features, including spam control, database support, convenient record management, and many others.
according to a recent study, more than 30% of publicly accessible mail servers in the world run postfix. so there is a lot of useful documentation available that can help users adapt much faster.
postfix features
- postfix implements top-notch defense mechanisms against spambots and malware while allowing administrators to take advantage of additional filtering software.
- comes pre-packaged with a powerful content filter, access control, virtual domain support, configurable status notifications and much more.
- offers significantly better performance, logging over 300 email deliveries per second from a single postfix instance.
- this linux mail server supports many standard databases including mysql, memcache, sqlite, postgresql, ldap, cdb and berkely.
download postfix
3. zimbra mail server
zimbra collaboration suite (zcs) is an open source software framework that provides a powerful yet efficient mail server for linux users. offers a robust set of additional features, including group calendars and document sharing with flexible tooltips, drag-and-drop elements, and convenient UI menus.
zimbra ships private and public cloud ready and offers an innovative mobile web client application. they also provide an immensely powerful closed source enterprise edition.
zimbra email server features
- zimbra offers real-time backup and restore capabilities, allowing businesses to focus more on their services than security.
- robust disaster recovery with One click makes it easy to restore sensitive data. information in case of server failure.
- zimbra comes with powerful migration tools that make transferring messages easy and efficient.
- allows administrators to schedule emails conveniently using filters like future date, time, and even time zone.
- The robust web management console provided by this linux email server makes managing your requests easy.
download zimbra mail server
4. oxygen
axigen is powerful email server software with a robust set of innovative features to make email management easy. provides a massive collection of pre-built features, such as a built-in mailing list server, malware and spam protection mechanisms, and various mobile capabilities. most linux distributions support axigen, but the server is not free. however, axigen also offers a free version with support for up to 5 domains, 5 groups, and 5 users.
axigen characteristics
- This linux email server is local software, which means it can be hosted in data centers, bare metal, or in private/public clouds.
- axigen provides a convenient address book, a tool to import/export contacts, robust filtering mechanisms and an innovative mobile webmail interface.
- offers modern security tools such as encryption, multi-layer access control, blacklisted contacts /whitelisting and password expiration rules.
- axigen can access users’ emails from external sources like gmail, yahoo! mail and access messages directly from smartphones.
download axigen
5. citadel
citadel is, without a doubt, one of the best open source mail server software available at the moment. it is an old server software and it stood the test of time due to its flexible features and superior performance. citadel is a groupware software and collaborations happen very frequently.
It was designed to run on linux and bsd unix distributions but is compatible with most systems. this linux server tool is known for its simple yet useful control panel along with its efficient runtime.
characteristics of the citadel
- citadel comes with its own implementation of standard server protocols such as smtp, imap, sieve, pop3, groupdav and xmpp.
- provides a convenient address book, scheduler, file storage, and jabber along with ssl/tls encryption for all protocols.
- citadel is compatible with openldap and microsoft active directory and can be used for high-speed server-to-server replication.
- uses the berkely db to store all its content, including messages and the knowledge base.
download citadel
6. sendmail
Now known as proofpoint, sendmail is one of the oldest and most widely used mail transfer agents on unix platforms. it is a general purpose internetwork mail routing facility that provides a versatile set of delivery methods for sending mail over the internet.
this mail server software is written by eric allman and is custom licensed. sendmail used to dominate the email server scene before the advent of modern mail server software such as exim and postfix.
sendmail features
- sendmail is exceptionally reliable and makes sure every message is delivered to the right destination without much trouble.
- requires very low network bandwidth because it can pool addresses on a single host .
- sendmail allows users to specify custom email forwarding functions without modifying domain-wide aliases.
- instead of compiling configuration statements before runtime , sendmail uses configuration files to control mail configuration.
download sendmail
7. qmail
qmail is a widely used mail transfer agent that was initially developed as an alternative to the sendmail program. it is written using the c programming language and therefore offers more than efficient performance. qmail employs various security measures to reduce spam mail as much as possible and provides an easy way to set up user-defined mailing lists. qmail is freeware and a great choice for people looking for open source mail server software.
qmail features
- qmail is available on a large number of platforms, including linux, solaris, mac osx, and bsd.
- comes with built-in support for the ezmlm mailing list manager, verps, and automatic configuration
- This linux mail server software design is extremely modular and allows users to quickly replace some of the software with other modules.
- qmail allows users to manage your custom mailing lists and supports automatic mail loop prevention.
download qmail
8. modaboa
modoboa is a modern mail transfer agent that provides users with a powerful mail hosting and management platform. It comes with a simple yet effective web-based user interface that makes managing the mail server completely easy. The software is known for its versatility and allows for easy integration with popular MTA software such as Dovecot and Postfix. it uses a sql database as its central point of communication and is written using python.
modoboa characteristics
- This linux mail server software’s robust administration panel makes managing domains, mailboxes, and aliases easier than ever.
- modoboa features an innovative built-in monitor that allows users to view their server traffic through handy filtering features.
- uses standard server protocols like dkim and dmarc to make sure every mail is delivered correctly.
- modoboa comes with a handy calendar that allows administrators to manage hectic schedules much more conveniently.
download boa mode
9. email
if you are looking for a full open source mail server for linux and bsd distributions then iredmail is a great choice for you. is a powerful tool with features focused on security, privacy, and secure management. the software consists of all open source components, and an active development community makes sure that bug fixes and frequent updates are made from time to time. their professional technical support also ensures that your communication is not interrupted in the event of a system failure.
iredmail features
- iredmail establishes all its mail services using secure connections (pop3/imap/smtp over tls, webmail over https).
- implements powerful encryption mechanisms such as ssha512 and bcrypt (bsd) to store passwords.
- iredmail’s robust web user interface makes managing emails, folders, and sieve filters very intuitive and efficient.
- provides a versatile set of options storage for the backend, including openldap, mysql, mariadb, postgresql.
download iredmail
10. mail in a box
mail-in-a-box is an innovative modern linux mail server with a primary focus on easy implementation. Each instance of this email server provides a convenient webmail and imap/smtp server with automatic dns configuration. It also allows administrators to backup their mail server to amazon s3. Free TLS (SSL) certification of this software is provided through Let’s Encrypt. the software employs security best practices to ensure that all communications are handled securely and significantly reduces the attack surface.
mailbox characteristics
- comes pre-installed with modern mail protocols such as spf, dkim and dmarc along with extremely strong encryption.
- mail-in-a-box allows users to host email for multiple domains and users.
- the software is licensed under gnu gpl 3 and therefore requires no charge.
- comes with built-in support for spam filtering, greylisting and site hosting static websites along with many more.
download mail-in-a-box
11. kolab collaborative software
kolab groupware is an open source collaboration suite that features many web utilities, such as an email server and various web interfaces. The open source mail server provided by this suite is superior to many enterprise-grade products and can be used to send large-scale emails on a consistent basis.
no matter how much traffic you intend to handle, kolab allows you to do it very efficiently. It also has an enterprise edition that offers top-notch technical support along with additional premium features.
kolab groupware features
- kolab groupware has built-in support for all standard web protocols like smtp, pop3, imap and dane along with activesync and sieve.
- offers outstanding core storage support and can be easily integrated with directory service, mail delivery systems and other assets.
- kolab allows administrators to filter emails based on predefined criteria and reduces spam as much as possible.
- Users can save and share files from anywhere using kolab’s built-in cloud service.
download the kolab collaborative software
12. james apache
Apache James, also known as Apache Enterprise Java Mail Server, is a powerful Linux email server software developed and maintained by the Apache Software Foundation. This program is written entirely in the Java programming language and provides some of the most sought after email server functionality. Apache James’s modular architecture makes it more efficient than many traditional mail servers and allows users to assemble their mail server using off-the-shelf components.
james apache features
- this email server comes with native support for smtp, lmtp, pop3, imap, managesieve and jmap.
- apache james allows users to choose from a wide range of storage options , including mysql , postgresql, hsqldb, cassandra and elasticsearch.
- can be managed via jmx or the command line along with robust rest api.
- the software is fully standalone and is you can easily extend for additional functionality using custom plugins.
download apache james
13. messaging mail server
messenger mail server is a proven mail transfer agent offering individual services for esmtp, imap, pop3, smap, webmail and mailing list. It is widely known as an IMAP server and runs on all posix compatible platforms including Linux, Mac OS X, FreeBSD and Solaris. the software is marketed under gpl terms and is therefore free to use and modify. it is written using a combination of c, c++, and perl programming languages.
messaging mail server characteristics
- this mail server software supports many standard databases including berkeley db, mysql and postgresql.
- the web-based configuration and administration tool for mail servers Messaging makes email management much more convenient.
- offers a built-in imap/pop3 aggregator proxy that can distribute all mailboxes across multiple servers.
- messenger mail server comes with built-in email filtering mechanism which helps reduce spam significantly.
download messaging mail server
14. zentyal server
zentyal is an open source email and groupware solution based on ubuntu and is available for all major unix distributions. it is not just your everyday linux mail server but can be seen as a complete network administration package. It offers proprietary and community editions and is designed to meet the ongoing communication demand of small and medium-sized businesses. some of its additional features include directory and domain server, proxy gateway and mobile sync.
zentyal server characteristics
- offers a powerful antivirus and mail filtering mechanism to reduce spam and thwart email attacks.
- zentyal comes with built-in support for unlimited virtual mail domains and email authentication. single sign-on.
- the mail server supports activesync and webmail along with smtp, pop3, imap, caldav and carddav protocols.
- zentyal’s professional technical support makes it a suitable option for companies.
download zentyal server
15. midget mail server
dwarf mail server is a simple yet useful linux smtp server with a rich set of email management features. it uses the smtp, pop3, and imap4 rev1 protocols to deliver and route email over the internet and can handle unlimited virtual domains.
This server software is based on the dwarf framework and therefore shares many common design principles and features. In general, the dwarf mail server is a lightweight alternative to full mail transfer agents.
dwarf mail server features
- the dwarf mail server comes with built-in agents that provide a flexible logic layer and offer robust mail filters.
- the software is built on top of java and is therefore compatible with a wide range of standard platforms. , including ms windows, linux/bsd and macos.
- allows administrators to configure and activate their mail servers simply by changing a few lines of code.
- dwarf mail server uses the java™ platform security architecture along with ssl/tls for secure communication.
download dwarf mail server
16. open exchange mail
open-xchange is a powerful and efficient web collaboration suite that provides a powerful mail server for linux enthusiasts. the software requires a paid subscription, but users can try its community edition to see if it fits their requirements.
Email functionalities provided by your server software include secure webmail, convenient contact management, intuitive scheduler, and a useful set of superior email protocols. All in all, open-xchange mail is a suitable option for companies.
characteristics of open exchange mail
- open exchange mail allows administrators to host their email servers personally or in their dedicated clouds.
- the webmail feature provided by this mail server software is extremely solid and meets modern standards. .
- leverages dovecot’s imap server to provide superior email delivery speed and efficiency.
- open-xchange mobile apps allow users to manage their emails on the go. anywhere and anytime.
download open-xchange mail
17. cyrus image server
cyrus imap server is a robust linux mail server developed in the early 1980’s at carnegie mellon university. it was a very advanced project for its time and turned out to be a significant success. the software is now available as an open source mail server, and anyone can modify it to match their email needs. it offers a fairly modest set of features, such as multi-protocol support, powerful mail filtering mechanisms, and asynchronous read/write connections.
cyrus imap server features
- the file system used by this server’s mail queue is similar in design and format to qmail, courier, dovecot, etc.
- cyrus imap server provides mail filtering solid using the mail filtering language sieve.
- allows integrated email and calendar solutions via the caldav and carddav protocols.
- the software is still under active development, which means bug fixes and updates of software are available from time to time.
download cyrus imap server
18. webmail horde
horde webmail is a free groupware solution that offers powerful email management and delivery capabilities for today’s linux users. is a browser-based communication suite that can be used by businesses and offers a massive set of features and add-on modules.
Although we found the software difficult to set up at first, its convenient web-based interface makes administration a breeze. All in all horde mail server is a feasible solution for people looking for complete mail servers.
horde webmail features
- offers robust message search and filtering methods with a built-in spell checker and keyboard navigation support.
- horde webmail allows users to download message attachments in a zip file and set up handy aliases.
- uses s/mime and pgp tools to conveniently encrypt and sign emails.
- users can get a conversation view of their messages directly in a thread.
download horde webmail
19. mailerq
mailerq is a very high performance linux mail server that is developed to handle large scale email requests efficiently. is a modern solution that integrates some of the best practices in email management. some of its features include real-time monitoring, advanced comment processing, and secure email connections. however, the software is not free and requires a hefty fee. therefore, it will be a good solution for companies that are willing to pay for its service.
mailerq features
- mailerq’s robust management console provides real-time information on email delivery attempts, queues, error logs, and much more.
- allows administrators to classify delivery patterns response to your messages and process them based on comments and responses from the server.
- mailerq was the first mail transfer agent to use the arc (authenticated received chain) authentication method.
- administrators can schedule future messages very conveniently through the help of predefined email throttling schedules.
download mailerq
20. mailbox
maildrop is a lightweight yet powerful mail delivery agent that provides free disposable email addresses for web forms. it is written using the c++ programming language and therefore offers extremely efficient performance. the software is under active development and new updates with bug fixes will continue to arrive. This linux mail server software receives your messages from stdin and can deliver them in maildir and mbox formats. it is a useful tool for many and has various uses.
maildrop features
- maildrop can be used anywhere users do not want to provide their real email addresses.
- employs extremely powerful modern spam filters that remove most spam emails efficiently.
- The open source nature of this mail delivery agent allows users to modify the tool to fit their email requirements.
- is more faster than many traditional mail delivery agents due to its low resource usage.
li>
try maildrop
final thoughts
Mail transfer agents are often very diverse depending on their intended use and often have seemingly different characteristics. most full linux mail servers come with filtering mechanisms, address book and encryption methods along with other necessary items.
Our editors have gone through a substantial list of such email servers and have outlined the top 20 linux mail server options for you. Hopefully, we were able to provide you with the insights you were looking for in this guide. thanks for sticking with us, and don’t forget to keep coming back for additional linux guides and how-to’s.