Best Linux Mail Servers You Should Check in 2024

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In our mobile-first world, we can send and receive information from one corner of the world to another by simply hitting a "Send" button. Most of us enjoy these features of social media applications and email systems, but we give no thought to understanding the mechanism constructed behind the scenes. When considering an email message, we must look at how it travels from the organization's point to its destination. Let's understand the best Linux mail server you should pick in 2024.

Before diving into some long-established technical standards, we can be sure because there would be more than one checkpoint for the message to reach its final destination. These checkpoints are called mail servers, and the organization's point is known as an email client. You can treat a mail server as a friendly mailman who takes multiple turns before delivering your mail. 

When considering multiple mail servers, we need to understand how they communicate and what protocols are in place to authenticate each message.

What is a Mail Server?

Mail servers are computerized systems that can send and receive emails. This system is usually a combination of many interconnected servers that help each other send the message to the right recipient. Sending an email may take only one second, but it involves a series of transfers from one mail server to another. If you take away the rest of the Linux mail servers that are not within your domain reach, you are limited to sending emails to only those whose email addresses match your domain. 

What is an Email Client? 

Email clients differ from mail servers as they help messages travel over the internet through multiple servers to reach the final recipient. They do not handle storage facilities like the servers and must be connected to the shared network. Some of the most common email clients are Outlook and Gmail. These email clients create an interface for users to organize and categorize their messages. One can even handle attachments like images or documents in their messages using an email client. 

An email server can be set up on a:

• Desktop Computer
• Laptop
• VPS
• Dedicated Server

We recommend the last two options as it is much more reliable. Unlike a home computer, these servers are online 24/7 and are hosted on premium data centers equipped with enterprise hardware. 

Email Mechanism 

The email mechanism has been around for decades, but it always came with some other limitations. If we go back a few decades, we will witness only a single mainframe system for sending and receiving messages. We follow unique protocols that allow us to form interconnections between different mail servers. By forming a shared network with multiple mail servers, we have integrated the internet to allow the servers to communicate. This communication channel is not a single-step operation; it flows through a series of servers to reach its destination. To make it easier for you to understand, we have highlighted the message flow with the below listed step-by-step. 

Step 1- Writing emails is done using an email client. It can be from Apple Mail or Google's Gmail. After you write your message and hit the send button, your email client automatically connects to your domain's server. 

Step 2- The server then interacts with the client to attain information such as the recipient's email address, the body of the message, and any attachments. This is done to help the server locate the recipient's destination. 

Step 3- To initiate the transfer, the server follows a standard protocol called "Simple Mail Transfer Protocol." SMTP involves the server searching for the recipient's domain name and locating the final server near its destination. The recipient's domain name is acquired using a DNS server, and it makes contact with the destination mail server, also known as Mail Exchanger (MX). 

Step 4- After the mail transfer agent locates and delivers to the final destination, the recipient accepts the message through two main protocols: Post Office Protocol (POP) and Internet Message Access Protocol (IMAP). 

The SMTP servers play a huge role in sending and receiving messages because they perform scans at both ends to authenticate the usernames and domain names. The protocols change for each organization, and aligning your requirements with an emailing process is necessary. 

Advantages of Mail Servers 

Many people wonder why installing mail servers is beneficial. It is not their fault because we can argue that the cost of hardware and electricity can be a bit too much from one perspective. This may be true for small businesses managing a couple of hundred mail accounts, but in other cases, mail servers provide immense value, and here are some advantages to prove it:

• You get your emails instantaneously, and there is no delay at all. When you install a mail server with your domain name, all outside mail will directly come to you, with zero waiting time. If you don't have a mail server in place, the sending machine will likely implement a back-off algorithm that makes the message bounce from one server to another. The time delay will increase in such cases, and a bad internet connection would only cost you more. 
• Internal emails are sent to the destination instantly after hitting the send button. Everyone is likely to have the same domain name within an organization, so having a mail server can process the message almost instantly. The best part about using mail servers for internal communication is it does not depend on Internet access and attachment size. 
• Mail servers give you complete control over the list of users so that you can add or delete users at any given point in time. This is usually not possible with Internet Service Providers because they limit how many users you can have. 
• Mail servers take care of spam filtering and virus scanning to another level that no ISP can match. The problem with an ISP is that they have complete control over authentication and scanning operations, but with a mail server, you will be the one to take over. 
• Special emails for printers and faxes can also be executed using your mail server. You can automatically print a copy and send a fax of requested documents. 

Things to Consider Before you Select a Mail Server 

1. Functionality

In the last decade, mail servers' functionality drastically increased from sending, receiving, and providing access to different messages. These servers' functionality is always associated with core features such as POP, SMTP, and WebMail. Still, you can also add specific functionalities for your mail server to maximize its potential. 

2. Scalability 

When you are an organization looking to expand, you must consider the scalability factor to support thousands of users. To understand the scaling of mail servers, you need to know your company's product support system and monitor the IO subsystem's performance. These can give you a fair idea of how much more hardware you require to meet. You should also consider the logging and service usage level to have a more precise number. 

3. Ability to Integrate

If you spend a fortune on mail servers, you likely want to integrate them with other software to ease business operations. To know whether a mail server can co-exist with other software, you need to assess the mail server's architecture and inner workings. Speed and efficiency can be used to determine whether a mail server has the required architecture to integrate third-party software successfully. 

4. Migration Facilities

If you are requested to transfer data from one mail system to another at some point, it will cost you a lot of money. That is why you should choose a server having migration facilities with either MBOX or MDIR format. You can also migrate configuration data if the servers have access interfaces. 

5. Security 

Security features are highly important when it comes to managing mail servers. Many providers give not one but several authentication features to restrict unauthorized access. You should also consider having a responsive alert system for your mail server. This way, you are immediately notified when there is a security issue. Other security features are IP-based authentication, SMTP filtering, and RealTime Black-Lists. 

We highly recommend reading the difference between Bulkmail and Spam to understand further the mechanisms of mail servers and 'mail' itself. 

6. AntiVirus and AntiSpam Management 

It is important to prevent malware from entering your mail server because it can leak confidential messages to other servers. Some features to consider for antivirus management are attachment control, auto download of virus definition files, and multi-scan options. In the case of anti-spam management, you should look for download filters, sender checking, and mail reports. These tools can help you in any situation or emergency. 

10 Best Linux Mail Servers 

Now that you are clear with all the basic concepts surrounding mail servers, we are ready to dive into some of the marketplace's best Linux mail servers. To get a reliable mail server for your business and organization, you need to consider several features and do some heavy research around them. To save time, we have created a list of the best Linux-based mail servers that meet basic functionality and more. 

1.   Exim 

One of the top-rated mail servers in the marketplace by many experts is Exim. It is a mail server with various features, and each perfectly executes a specific operation. Customization and configuration abilities are the most significant advantage of using Exim as your mail server. 

It has the best transfer agents capable of adapting to any business environment, making customization easier. As this is a Linux-based mail server, the GNU GPL license allows administrators to modify the original software. 

Exim Mail Server Pros and Cons

Pros:

-On the plus side, Exim is a very versatile mail server that can be configured to suit various needs.

-It's also relatively easy to set up and administer, even for beginners.

-Exim is also highly efficient and can handle large volumes of mail well.

Cons:

However, there are some drawbacks to using Exim too.

-One potential downside is that it's not as widely used as some other mail servers (such as Postfix)

-so there may be less community support available if you run into problems.

-Exim can also be quite complex to configure if you need anything beyond basic functionality.

Overall, Exim is a good choice for a Linux mail server, especially if you need something that's highly configurable. However, it's worth being aware of the potential downsides before deciding.

2.   Sendmail

Sendmail is another top pick in our best mail servers list because it is the most reliable. As it doesn't need high network bandwidth, Sendmail can batch different addresses to a single host machine. 

When it comes to customization, it uses configuration files to run the instructions. Sendmail is also popular for its delivery methods, which follow standard protocols. 

Sendmail Pros and Cons

We’ll go over some of the pros and cons of using Sendmail so that you can decide if it’s the right choice for you.

Pros:

-Sendmail is a very stable and reliable mail server. It’s been around for a long time and is used by a lot of big organizations.
-It’s easy to set up and configure. 
-It works well with other software, such as spam filters.

Cons:

-Sendmail can be complex to configure if you want to do more than just the basics. 
-It doesn’t have a lot of bells and whistles like some of the newer mail servers.

3.   hMailServer

Free Linux mail servers are also reliable for global operations, and one of the most flexible mail servers is the hMail server. It being open-source allows everyone to download the software without spending a penny. 

The main protocols in use for hMail servers are IMAP, SMTP, and POP3. The ability to integrate is present, and on top of that, it can also run multiple antivirus scans on incoming and outgoing emails. 

hMailServer Pros and Cons

We'll discuss the pros and cons of using hMailServer so that you can decide if it's the right choice for your needs.

Pros:

-hMailServer is free and open source. This means you can customize it to meet your specific needs without paying for a license. 

-hMailServer is very easy to install and set up. Even if you've never used a mail server before, you should be able to get hMailServer up and running in no time. 

-hMailServer offers many features, including support for multiple domains, multiple users, POP3, IMAP, SMTP, and more. You can also add additional features via plugins. 

-hMailServer is very stable and reliable. It's been around for over 10 years and has been used by thousands of companies and organizations worldwide.

-hMailServer has excellent documentation. If you need help setting something up or troubleshooting an issue, chances are you'll be able to find the answer in the documentation. 

Cons:

-Because hMailServer is open source, no official customer support is available. You'll need to rely on the community for help if you run into an issue. 

-hMailServer is not as widely used as some of the other mail servers out there. This means fewer resources (such as tutorials and how-tos) are available. 

-hMailServer lacks some of the advanced features that are available in other mail servers. For example, it doesn't offer spam filtering or antivirus protection.

4.   Axigen 

A robust mail server that comes with many innovative features is Axigen. It takes email management to another level by having a massive collection of predefined functions for specific operations. Axigen also has various mobile capabilities, making it more compatible with other platforms and systems. 

The free edition of Axigen is limited to only five users, so you better go with a professional plan to access all features. The interface of Axigen is easy to understand and navigate. There is a tool for everything, and it also considers modern-day features like multi-layer access control. 

Axigen Pros and Cons

If you're considering Axigen, here are some pros and cons to help you decide.

Pros:

- easy to set up and use
- good documentation
- supports multiple domains
- offers a wide range of features

Cons:

- not as widely used as some other mail servers, so there may be fewer resources available if you run into problems
- no webmail interface

5.   Zimbra 

Zimbra is another open-source Linux mail server on our list, but this is more powerful and efficient than a Linux distribution. It creates a friendly user environment by providing additional features like group calendars and convenient UI menus. 

The recovery solutions of this mail server are impressive as it focuses beyond security. Zimbra also equips its users with a one-click disaster recovery feature that makes it more reliable in emergencies or server failure. 

Zimbra Pros and Cons

we'll examine the pros and cons of using Zimbra as your mail server.

Pros:

-Zimbra is a very feature-rich mail server, offering a wide range of options and tools for managing your email system. 
-It is relatively easy to set up and administer, even for users with little experience. 
-Zimbra offers good scalability, so it can grow with your business as your needs change. 
-The software is open source and, therefore, free to use. 

Cons:

-Zimbra can be quite resource-intensive, so it may not be suitable for use on lower-powered servers. 
-The interface can be somewhat confusing and overwhelming for new users. 

Overall, Zimbra is a good choice for a mail server for businesses of all sizes. It offers many features and flexibility but can be resource-intensive and difficult to learn for inexperienced users.

6.   Modoboa 

A modern-day mail server that can do everything at a high-efficiency rate is Modoboa. The methods are simple to execute and easy to integrate. To manage its communication channels between components, Modoboa uses a SQL database using Python. 

Administrators can easily adapt to the new control panel as it has a built-in monitor to help users understand the incoming traffic. Modoboa is capable of creating visuals with the help of several filtering facilities. The protocols in place for proper delivery are DKIM and DMARC. 

Modoboa Pros and Cons

we'll take a look at some of the pros and cons of using Modoboa to help you decide if it's the right choice for your needs.

Pros:

-One of the biggest advantages of using Modoboa is its ease of use. It features a clean and intuitive web interface that makes managing your mail server a breeze. You can easily add and remove users, create email lists, and even set up auto-responders without hassle. Modoboa has a wide range of plugins that allow you to extend its functionality as needed.

-Another benefit of using Modoboa is its security features. By default, Modoboa uses encrypted passwords and SSL/TLS connections to keep your data safe. Additionally, it offers several other security features that can be enabled, such as two-factor authentication and spam filtering.

Cons:

On the downside, one potential drawback of using Modoboa is its lack of documentation. While the web interface is fairly straightforward to use, there is not a lot of documentation available to help you if you run into problems. Additionally, because Modoboa is still relatively new, there are not as many third-party plugins or integrations available for it yet as there are for other mail servers.

Overall, Modoboa is a great choice for those looking for a secure and easy-to-use mail server. While it lacks some of the features and documentation of other mail servers, its clean interface and wide range of security features make it a good option for anyone looking to set up a new mail server.

7.   Apache James 

Apache James is a well-known software foundation with a modern server architecture. It offers a feature-rich mail server that can create unique solutions by adjusting the components. 

Linear scalability is possible with this mail server, allowing the changes to happen without disrupting the middleware. The configuration allowed to the user is vast, so one integrates well with other similar caliber technologies. 

Apache James Pros and Cons

we'll be taking a look at the pros and cons of Apache James so that you can make an informed decision about whether or not it's the right choice for you.

Pros:

-Open source software released under the Apache License 2.0 
-Can be run on most major operating systems (Windows, macOS, Linux) 
-Has a web interface for managing users and messages 
-Can handle large amounts of email traffic 
-Can be easily configured to work with other applications and services 

Cons:

-Not as widely used as some other mail servers, so there may be less community support available 
-May not have all the features that some users need

8.   Courier Mail Server 

Courier is one of the few mail servers that provide individual protocols like ESMTP or IMAP for meeting specific requirements and services. Linux, Mac OS X, and Solaris are major platforms compatible with courier mail servers. 

Admin panel is much more comfortable to use than other options in this list because it has a wide variety of web-based administration and configuration tools. Courier servers also have a unique integrated filtering mechanism to reduce spam emails. 

Courier Pros and Cons

We'll look at one of the most popular mail servers for Linux and discuss Courier's pros and cons.

Pros:

One of the most popular mail servers for Linux is Courier. Courier has many features that make it a great choice for many users. For example,

-it supports IMAP and POP3, so you can use it with most email clients.

-It also has a web interface that makes it easy to check email from any computer.

-Courier is also very configurable, so you can set it up to work how you want it to.

Cons:

-However, there are also some downsides to using Courier. One downside is that it can be difficult to set up. If you're unfamiliar with server administration, you may have trouble getting Courier up and running.

-Courier doesn't have as many features as the other mail servers we'll discuss below.

If you're looking for a simple mail server that's easy to set up and use, Courier might be a good choice for you. However, if you need more features or flexibility, you may want to consider one of the other options on this list.

9.  Cyrus IMAP Server 

It is another Linux mail server used in organizations having multiple protocol requirements. Cyrus mail servers come with robust system software having powerful mail filtering mechanisms. The software also uses Sieve filtering language to eliminate unnecessary messages in the users' accounts. 

Two protocols generate the email solutions, and they are CalDAV and CardDAV. An important point to note here is that this software is still in development, so there will be regular updates to fix errors and bugs. 

Cyrus IMAP Pros and Cons

we'll look at the pros and cons of Cyrus IMAP, one of the most popular Linux mail servers.

Pros:

- Can be easily integrated with other applications and systems
- Provides a wide range of features and options
- Excellent documentation and support
- Highly configurable
- Rock-solid stability

Cons:

- Requires a bit more technical expertise to set up and configure than some other mail servers
- Not as widely used as some other mail servers, so there may be less community support available

10. Postfix Mail server

A Postfix mail server is a free and open-source mail transfer agent (MTA) that routes and delivers electronic mail. Postfix is popular for setting up a mail server on a Linux system. It is easy to set up and configure and has a wide range of features. Postfix can be used with other software to create a complete mail server solution. Postfix created at IBM research and used instead of the Sendmail program. Postfix supports AIX, BSD, HP-UX, Linux, macOS X, and Solaris.

Postfix Pros and Cons

 we’re going to go over both the positive and negative aspects of using Postfix so that you can make an informed decision about whether or not it’s the right mail server for you.

Pros:

-It’s easy to set up and configure
-It has a low memory footprint
-It supports multiple domains
-It can act as a relay server
-It has a wide variety of options for security and anti-spam features

Cons:

-The configuration file can be confusing for beginners
-It doesn’t have a web interface

Conclusion

Linux Mail servers make tremendous contributions to mail management, making them more flexible and easy to operate. The protocols used to send and receive messages are also crucial to land a suitable mail server for your organization. The first step to achieving significant success with your mail server would be incorporating all the right features. 

If you are having trouble with viruses and spam emails, you must consider better authentication features with high-level filtering capabilities. We have listed some basic features in this article, but you need to list all the areas you need improvements in and fulfill them with respective functionalities. 

Our top ten mail servers have an excellent chance to increase speed, performance, and security levels. Make sure to check their official websites and explore plans one by one. You can also choose any of the above for Linux VPS hosting.