Top 15 Linux Mail Servers

It is fair to say that sending and receiving emails were our first connections to others through the internet. Emails are sent and received by mail servers based on a combination of many interconnected servers. In this article, top 15 Linux mail servers will be introduced to help you know and use them. This content would be useful if you have your own business since finding an ideal mail server enable you to manage your daily emails and enjoy other advantages of it.

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What is a Mail Server and How does it Work?

Computerized systems that can send and receive emails are called mail servers. This system typically consists of a number of connected servers that work together to transmit messages to the correct people. Even though it just takes a second to send an email, several transfers from one mail server to another are required.

Emails are moved from one Internet location to another using a Linux mail server program. They also go by the name Mail Transfer Agents (MTAs), and they are responsible for receiving incoming emails from other servers and passing them to the user’s client software and back again. Despite the fact that almost all mail servers are capable of handling both incoming and outgoing emails, the two tasks are distinct and adhere to different protocols. The Post Office Protocol 3 (POP3) or the Internet Message Access Protocol (IMAP) are typically utilized by an incoming mail server, and the Simple Mail Transfer Protocol (SMTP) is employed to deliver emails that have already been received from the user’s client software.

A small mail server can be all you need if your business is small and only has a few users. A more powerful server will be required if you have a high number of users. stay with us to review the Top 15 Linux Mail servers to find out which one meets your needs and covers your specific situation. Before that, you need to know how to choose an ideal mail server for Linux.

Options Must be Checked while Choosing a Mail Server

There are several factors to take into account when choosing a mail server. Let’s review the most important features that you must consider when you want to select a mail server.

1. Security

When it comes to administering mail servers, security features are crucial. To prevent unwanted access, many providers offer not just one but numerous authentication features. A responsive alarm system for your mail server is something else you should think about. In this manner, if there is a security issue, you are informed right away. SMTP filtering, Real-time Black-Lists, and IP-based authentication are further security features.

2. Scalability

You must take into account the scalability element to handle thousands of users when your firm is aiming to grow. You must be aware of your company’s product support system and keep track of the IO subsystem’s performance in order to comprehend the scaling of mail servers. These might help you determine how much additional hardware you will need to meet. To obtain a more accurate figure, you need additionally take into account the amount of service consumption and logging.

3. Integration

If you invest a lot of money in mail servers, you probably want to combine them with other company software to make operations easier. You must examine the design and internal workings of a mail server to determine whether it can coexist with other programs. It is possible to tell whether a mail server has the necessary architecture for successfully integrating third-party software by looking at its speed and efficiency.

4. Functionality

The ability of mail servers to send, receive, and provide access to various messages has significantly increased during the past ten years. The operation of these servers is always linked to fundamental components like POP, SMTP, and WebMail. To improve the functionality of your mail server, you can also add particular features.

5. Management of Antivirus and AntiSpam

Malware can leak private communications to other servers, thus it’s crucial to keep it from getting into your mail server. Attachment control, automatic virus definition file downloads, and several scan options are a few aspects to take into account for antivirus management. You should look for download filters, sender checks, and mail reports while managing anti-spam. You can use these tools to assist you in any emergency or scenario.

6. Migration Support Services

It will cost you a lot of money if you ever need to transfer data from one mail system to another. Because of this, you ought to pick a server with support for MDIR or MBOX format migration. If the servers provide access interfaces, configuration data migration is also possible.

Top 15 Linux Mail Servers

In this part, you will be familiar with the best mail servers for Linux and learn about their pros and cons to be able to decide what suits your needs. Let’s get started.

1. Exim

Exim is regarded by many experts as one of the best mail servers available. It is a piece of free software that is present in the majority of UNIX-like operating systems. On Debian Linux systems, its fourth version serves as the MTA by default. Exim is a mail server with a number of capabilities, each of which flawlessly completes a particular task. The most important benefit of utilizing Exim as your mail server is the flexibility it offers in terms of customization and configuration. It features the best transfer agents, which can easily customize to any corporate setting. The GNU GPL license permits administrators to alter the original program because this mail server runs on the Linux operating system.

Overall, if you require a Linux mail server, Exim is a solid option, especially if you need something that is extremely flexible.

Exim Advantages

• Even for newbies, setting it up and managing it is rather simple.
• GNU GPL license0.
• Exim is also very effective and adept at managing high mail volumes.
• System-wide message filtering.
• Exim is a highly adaptable mail server that may be set up to meet different requirements.
• Encrypted SMTP connections using SSL/TLS.
• The external authenticator.

Exim Disadvantages

• If you encounter difficulties, there might be less community support accessible.
• Exim can be difficult to configure if you require features above the bare minimum.
• The fact that it’s not as popular as some other mail servers could be a drawback.

2. Zimbra

Zimbra is one of the top 15 Linux mail servers. This surpasses a Linux distribution in terms of power and effectiveness. Offering extra features like group calendars and practical UI menus fosters a welcoming user experience. This mail server’s recovery options are impressive since they go beyond security. An open-source, potent Linux mail server with many capabilities is called Zimbra Email Server. It is scalable, safe, and simple to use. It also supports a wide range of hardware and operating systems. It is therefore a fantastic option for companies of all sizes. Additionally, Zimbra has a fantastic user base that is constantly prepared to lend a hand.

Zimbra offers users a one-click disaster recovery tool that increases its dependability in urgent situations or server breakdowns. It is a fantastic choice if you’re seeking an email server that can accommodate your needs. It is well known for its dependability and security and has been used by millions of people worldwide.

Overall, organizations of all sizes should consider using Zimbra as their mail server. Although it has a lot of features and flexibility, it may also be resource-intensive and challenging for beginners to master.

Zimbra Advantages

• Free and open-source.
• Zimbra has high scalability, so it can develop alongside your company as your demands alter.
• Mobile web client application.
• Even for those with little experience, it is comparatively simple to set up and administer.
• Backup feature.
• Zimbra is a very feature-rich mail server that offers a variety of choices and tools for controlling your email system.
• Group calendars and document sharing.

Zimbra Disadvantages

• For new users, the interface can be a little daunting.
• Zimbra may not be appropriate for usage on servers with lower processing power because it can be rather resource-intensive.

3. Sendmail

Sendmail is also one of the top 15 Linux mail servers that can also be used in Windows NT. The first version of Sendmail, a general-purpose email routing system, was launched in 1983. Sendmail is a well-known MTA that offers a flexible selection of email delivery methods and is free. Sendmail can batch-send different addresses to a single host machine because it doesn’t require a lot of network capacity. It uses configuration files to execute the instructions when it comes to customization. The fact that Sendmail uses protocols-compliant delivery techniques has contributed to its popularity.

A Sendmail server makes an effort to deliver emails to their intended recipients as soon as they are received. It puts messages in a queue to be sent later if the recipient is absent. In actuality, it offers no mailbox services. Therefore, additional software is required, such as POP3 and the Internet Message Access Protocol.

Sendmail Advantages

Requires little network bandwidth.

It’s simple to configure and set up.

Customized email forwarding capabilities.

It integrates effectively with other programs, such as spam filters.

An extremely dependable and stable mail server is Sendmail. Many large firms utilize it, and it has been around for a while.

Sendmail Disadvantages

• The sendmail configuration might be difficult if you wish to perform more than the bare minimum.
• It doesn’t have as many frills like bells and whistles as some of the more recent mail servers.

4. Qmail

One of the best and most popular Linux mail servers is Qmail. It is a great substitute for Sendmail. The SMTP protocol confirms this claim by supplying various credentials through the queue manager or the SMTP sender, and security is the largest benefit it offers consumers. It is regarded as one of the top 15 Linux mail servers due to its popularity and ease of use during settings. As a simple email manager, it is easy to use Qmial and it is stable enough to provide a safe environment

Qmail Advantages

• Support for QMT.
• Allows you to replace any single part of the system with an alternative module.
• VERPs, the EZMLM mailing list management, and automatic host configuration are provided.
• Supporting a variety of operating systems, including Linux, Solaris, Mac OS X, and BSD.
• Managing customized mailing lists and assisting with the automatic detection and avoidance of mailing loops.
• Wildcard mailboxes with user control.

Qmail Disadvantages 

• It doesn’t allow internet connections using IPv6.
• Many options, such as those for outgoing SMTP messages, etc., have hard-coded higher limitations.
• The account cannot be configured using a regular procedure. The overall design is written to maintain a static interface.
• The user may become confused by the queue structure used to keep the emails.
• Although Qmail is open source, it is not free to use. Its distribution is noticeably slower, and sending customers binaries is not an option.

5. Citadel

Unquestionably among the greatest mail servers for Linux is Citadel. This powerful and highly versatile email architecture has stood the test despite being released 33 years ago thanks to its exceptional performance and adaptable features. This mail server is a general-purpose groupware and collaboration suite that is made to work with BSD UNIX distributions and open-source operating systems like Linux. It stores all of its data in the Berkeley Database.

It is free and open-source software that operates under the GNU General Public License. (GPLv2 and GPLv3). Most people are familiar with this Linux mail server for its straightforward control interface and quick startup.

Citadel Advantages

• OpenSSL encryption.
• Easy to install and use.
• Scheduler.
• Built-in implementations of Internet Protocols.
• Keeping files.
• Multiple domain support.

Citadel Disadvantages

• Clunky interface.
• Complex configuration for novice users.

6. hMailServer

Another free, open-source Linux mail server that is well-liked across numerous industries is hMailServer. SPF and SURBL are two of the built-in anti-spam technologies. It supports popular protocols like SMTP, POP3, and IMAPP. It is also related to a high-security feature that permits authentication and has a straightforward installation and setting process. It can attach to your virus scanner to scan all incoming and outgoing emails and includes customizable score-based spam protection.

hMailServer Advantages

• Free and open source.
• It’s quite simple to set up and configure. You should have no trouble setting up hMailServer, even if you’ve never used a mail server before.
• Multi-domain supports.
• Using plugins, you may also add more functionality.
• hMailServer is extremely dependable and stable.
• SSL encryption.
• Website administration.
• If you need assistance configuring something or debugging a problem, you probably can find the solution in the manual.

hMailServer Disadvantages

• Some of the more sophisticated capabilities seen in other mail servers are absent from -hMailServer. It doesn’t provide antivirus protection or spam filtering, for instance.
• Not as many people use -hMailServer as some of the other mail servers available. As a result, there are fewer resources available.
• There is no formal customer assistance offered because hMailServer is open source. If you encounter a problem, you’ll have to rely on the community for support.

7. Modoboa

One of the best open-source SQL-based Linux mail servers is called Modoboa. It provides a number of essential capabilities from a single user interface, eliminating the need to install each feature separately. Let’s Encrypt, a non-profit Certificate Authority provides a private and secure mailing option utilizing the TLS protocol. Additionally, it frees you from reliance on email service providers.

Using DMARC, Modoboa is frequently used with the SPF and DKIM protocols. Through a reporting feature, these protocols, which are free email authentication methods for email delivery and security, assist senders and recipients in enhancing and monitoring the domain’s defense against phishing emails. The nice thing about it is that it enables you to set up a fully-functional mail server by utilizing the most crucial features you may benefit from.

If you’re looking for a safe and user-friendly mail server, Modoboa is an excellent option. Anyone wishing to set up a new mail server will find it to be a suitable alternative due to its straightforward interface and extensive security features.

Modoboa Advantages

• Ease of use.
• The web interface is simple and easy to use, which makes operating your mail server a joy.
• With the help of a variety of plugins, Modoboa’s capabilities can be increased as necessary.
• Calendars & Address books management.
• Uses SSL/TLS connections and encrypted passwords to protect your data.
• Traffic monitoring.
• offers a number of additional security measures that can be set, including spam filtering and two-factor authentication.

Modoboa Disadvantages 

• Lack of documentation. If you have difficulties, there is not a lot of documentation available to assist you.
• Compared to other mail servers, it does not currently have as many third-party integrations or plugins available.

8. Postfix

Postfix is now offered under the Eclipse Public License after being first made available in 1998 under the IBM Public License 1.0. VMailer and IBM Secure Mailer are other names for Postfix. It is compatible with every UNIX-like operating system that has a C compiler and POSIX development environment, including BSD, AIX, HP-UX, Linux, macOS, and Solaris. You can route and deliver emails using this robust open-source mail server. It serves as the standard message transmission agent for NetBSD, macOS, RedHat/CentOS, and Ubuntu.

For setting up a mail server on a Linux system, Postfix is frequently used. It includes a variety of features and is simple to configure. A complete mail server solution can be made using Postfix in conjunction with other applications.

Postfix Advantages

• Secure and Fast.
• Easy to install and set up.
• Takes up little memory.
• Virtual domain support.
• It has numerous security and anti-spam features.
• Support for MYSQL, SQLite, PostgreSQL, LDAP, Memcached, CDB, and Berkeley Database.
• Pre-packed content filtering.
• It has the ability to serve as a relay.

Postfix Disadvantages

• Beginners may find the configuration file perplexing.
• There is no web interface.

9. Mail-in-a-Box

One of the top 15 Linux mail servers is Mail-in-a-Box which is a simple-to-use Linux mail server that makes use of cutting-edge security measures. In addition to automatic DNS configuration, spam filtering, greylisting, backups to Amazon S3, static website hosting, and simple SSL certificate installation, it also offers you other essential services. With the help of this tool, numerous users can receive hosted mail, DNS, webmail, and an IMAP/SMTP server for desktop and mobile mail programs.

Mail-in-a-Box Advantages

• Calendar and contacts synchronization.
• Certificates for free TLS (SSL) from Let’s Encrypt.
• Putting into practice the most recent security procedures, such as opportunistic TLS, strong ciphers, and HST, as well as contemporary mail protocols (SPF, DKIM, and DMARC).
• Setting up and configuring email with a web-based control panel.

Mail-in-a-Box Disadvantages 

• Complex setup processes.
• The presence of bugs.
• Software compatibility issues.
• Has an archaic user interface.

10. Cyrus IMAP Server

You can access your private emails using the IMAP protocol with the help of the robust Linux mail server known as the Cyrus IMAP server. It also includes services for contacts and calendars. Your company’s performance is enhanced by having numerous services connected to a mail server. Users can use IMAP, IMAPS, POP3, and POP3S to access the mail server. A private mailbox database that effectively optimizes the server for scalability and administration can be useful to you.

The system software on Cyrus mail servers has strong mail screening features. In order to remove pointless communications from users’ accounts, the software additionally employs Sieve filtering language. The email solutions are produced by the CalDAV and CardDAV protocols. The fact that this program is still being developed and will receive regular upgrades to correct faults and problems is crucial to keep in mind.

Cyrus IMAP server Advantages

• JMAP support.
• integrated with other applications and systems.
• Highly configurable.
• Significant documentation and support.
• Supporting antivirus and anti-spam toolkits.

Cyrus IMAP server Disadvantages 

• A little more complicated to install and configure than some other mail servers.
• Because it is not as popular as some other mail servers, there might not be as much community assistance.

11. Courier Mail Server

One of the few mail servers, Courier, offers unique protocols like ESMTP or IMAP to cater to certain needs and services. Major operating systems that are compatible with courier mail servers include Linux, Mac OS X, and Solaris. Admin panel features a far larger selection of web-based administration and configuration tools than the other choices on our list, making it much more comfortable to use. In order to cut down on spam emails, courier servers also include a special integrated filtering system.

Courier can be a decent option for you if you’re searching for a straightforward mail server that’s simple to install and use. However, you might want to have a look at one of the other choices on our list if you require more features or flexibility.

Courier Mail Server Advantages

• It offers a web interface that allows checking email from any computer simple.
• Courier is one of the most widely used mail servers for Linux. Due to its various features, Courier is a popular choice among users.
• It is very adjustable, allowing you to customize how it functions.
• You can use it with the majority of email clients because it supports IMAP and POP3.

Courier Mail Server disadvantages

• It could be challenging to set up. You could struggle to set up Courier if you’re not experienced with server administration.
• Compared to the other mail servers, Courier has fewer features.

12. SquirrelMail

One of the most well-known Linux mail servers is SquirrelMail, which is released under the GNU General Public License. The IMAP and SMTP protocols are both supported by this free server, which was created in PHP. Its pages are displayed in HTML 4.0 and it is simple to set up and utilize. It is extremely dependable and capable of handling massive volumes of mail. Spam filtering and security measures like SSL encryption are also supported by SquirrelMail. It works nicely with other programs like WordPress and may be used with the majority of popular web hosts.

Users who require a straightforward interface for reading and responding to emails should use SquirrelMail.

SquirrelMail Advantages

• Supports reading and sending HTML email messages.
• Easy to use interface
• IMAP protocol proxy server.
• Have an address book to store email addresses.
• Capable to search and flag emails.
• Spell checker.

SquirrelMail Disadvantages

• Does not support HTML composition.
• Interface issues because of updates lack.
• Its maintenance and security updates will be completely the server administrator’s responsibility in cPanel version 78 and above.
• SquirrelMail stopped providing security upgrades in 2013. Squirrelmail is consequently dropped from cPanel in version 78.

13. Horde

An email server, tasks and notes capabilities, contact management, and other features are all included in the webmail and collaboration package known as The Horde Project. The program was created using PHP and is distributed under the terms of the GNU General Public License. This Linux mail server is simple to use, operate, and scale up or down to suit your requirements. Any size organization can use it, and its personnel is always available to assist you with any inquiries or issues you may have.

Horde Advantages

• Has a mobile-friendly interface.
• Supports IMAP, POP3, 3-pane, and 3-column layouts.
• Supports News feed.
• Offers easy-to-navigate dashboard.
• Supports Calendar option.Users can create email filters and set preferences.
• Spell-checker.
• Supports mobile email access.
• Shared calendars, contacts, reminders, and IMAP files.

Horde Disadvantages

• Wrong per-user settings in the Horde interface.
• Partial database entries in the Horde database.
• Login failed issue due to configuration mistakes.

14. Apache James

The other top Linux mail server is the open-source Apache James which is an excellent solution for individuals who require an email server that can manage numerous emails because it is simple to set up and configure. Additionally, it’s ideal for companies that must adhere to stringent email standards. The Apache James server can be used independently or as a component of a larger system. It works with a variety of mail clients and supports the SMTP and IMAP protocols.

It provides a feature-rich mail server with the ability to build customized solutions by altering the parts. This mail server has linear scalability, thus modifications may be made without interfering with the middleware. The user has a wide range of configuration options, which makes it easy to interface with other technologies of a similar caliber.

Apache James Advantages

• Runs on the majority of popular operating systems (Windows, macOS, Linux),
• Open source software.
• Has a web interface for managing users and messages.
• Can easily be adjusted to operate with various services and apps and handle high email traffic volumes.

Apache James Disadvantages

• Because it is not as popular as some other mail servers, there might not be as much community assistance.
• Might lack some functionalities that some users require.

15. Axigen

One of the best mail servers that support POP3, SMTP, IMAP, and webmail is Axigen, which is available for Linux, Microsoft Windows, and Docker. It has groupware and collaboration features that may be used for free, including calendars, notes, tasks, and outlook connections. This mail server’s development started in 2003 and is based on cutting-edge proprietary technology. It accommodates all demanding customers, including both small and major service providers.

Offering a vast array of preconfigured routines for particular processes, it elevates email management to a new level. Axigen also offers a number of mobile features that increase its adaptability to different platforms and operating systems.
Only five users are permitted in the free version of Axigen, therefore if you want to use all the features, you should choose a professional plan. Axigen’s user interface is simple to comprehend and use. Everything has a tool, and it takes into account contemporary features like multi-layer access control.

Axigen Advantages 

• A convenient address book.
• Offers a wide range of capabilities.
• Highly configurable platform.
• It is simple to set up and use.
• Integrated Web-Admin and Web-Mail client.
• Has comprehensive documentation, and supports many domains.
• Integrated mailing list server.

Axigen Disadvantages

• It is less popular than some other mail servers, so if you encounter issues, there may be fewer resources available.
• Lacking a webmail interface.

Conclusion

Top 15 Linux Mail Servers That You Should Know and Use them were discussed in this tutorial. 15 best mail servers were explained and to help you detect which one should be your choice, the pros, and cons of them were also mentioned in detail. Depending on the unique requirements of your company, you can select any one of the top mail servers for Linux.

Keep in mind that the order of mail servers in this article has nothing to do with their superiority, it is just the author’s arrangement.