Finding the best Linux email client is largely a matter of taste. That said, there are specific email clients for Linux that are better than others. In this article, I'll share some of the best Linux email clients available.
Thunderbird – I know, everyone already knows about Thunderbird. But there are a few reasons why Thunderbird is still a major player. First, it's expandable with Thunderbird add-ons. This functionality allows one to turn it into a full personal information manager if they so choose to. You can add in a calendar and sync options for various cloud services (Microsoft, Google, etc). Plus, Thunderbird is easily themed. As expected, Thunderbird also comes with Baysian spam filtering included by default. So it may take a little training at first, but it usually catches on fairly quickly.
The email protocols that are supported include IMAP, POP and with add-ons, Microsoft Exchange. Note that for Exchange to work with two-way compatibility, you will need to install a working add-on. Same can be said with the calendar features, you will need to install the appropriate add-ons like Lightning and the backend(s) for syncing to your desired cloud services.
Thunderbird is useful for newbies and advanced users alike. I would also recommend it (with the right paid add-ons installed) for some business environments.
Claws Mail – If you're looking for something a bit less robust, simpler even – consider Claws Mail. The default theme feels dated for 2017, however its stability and function certainly make up for it. Claws Mail also supports POP3 and IMAP. Theme add-ons are also installable, however I must warn you none of them are outside of what you might see in most GTK apps. Basically you're looking at slight differences with the icons provided.
What I like most about Claws mail is that while it does support additional plugins, they're not really needed to get the most out of the application. With the default installation, Claws Mail gives you spam filtering, the ability to schedule when an email is to be sent and email rule creation. Thunderbird also offers rules, but I think Claws Mail's approach is a bit cleaner overall.
Claws Mail is useful for newbies and advanced users alike. Anyone that uses IMAP email would be quite happy with this application.
Evolution – In the GNOME application space, Evolution is considered to be a pretty solid personal information manager in its own right. Years ago, this was also Ubuntu's default email client. Using Evolution as a default email client might seem overkill as most people just want the email client itself, but Evolution is stable enough to provide basic functionality in addition to advanced stuff like calendar and task management.
At its core, the three main functions of the software are to offer all in one access to email, calendar and contact information. It's compatible with open source groupware and with the right plugin, can also work with some releases of Microsoft Exchange. Like other email applications for Linux, Evolution provides access to email rules, spam filtering and email scheduling. You'll also find the syncing options for various groupware suites to be fairly robust as well.
Email protocols supported include IMAP and with plugin(s) installed, various groupware suites including Microsoft Exchange. As touched on previously, Microsoft Exchange support is a bit hit and miss depending on the version of the groupware suite.
I recommend Evolution for those who need a usable groupware suite without depending on a multitude of add-ons to achieve decent personal information manager functionality.
Geary – When Geary first came out, I wasn't all that blown away as I was happily using other clients. For others out there, as it's easy to setup and stays out of the way. Geary supports simple setup and access for GMail, Yahoo! Mail, Outlook.com and other IMAP email.
Geary is a very basic client in that what you see is what you get. It doesn't provide spam filtering, but is stable and provides a reliable means of checking your email without any issues. Geary also feels relatively modern, despite its simplicity. And like all email clients mentioned in this article, Geary provides keyword searching and the ability to setup notifications.
Geary is a great email application for users wanting a simple to setup client that works flawlessly with IMAP.
Kmail – Kmail is a fantastic email program for users of the KDE desktop. It offers all the functionality of the email programs listed above, sans direct support of Microsoft Exchange. Some will point out that Exchange users could ask their system administrators for Exchange IMAP support, but that's hardly the same as direct Exchange support.
On the plus side, Kmail has a tremendous modern feel to it. Kmail supports various open source groupware suites, along with neat functionality like attachment compression. And of course Kmail also provides spam protection using technology like SpamAssassin and Bogofilter.
Best used with the KDE desktop due to the included KDE libraries, but you can use Kmail with other desktop environments as well. With its rich feature set, Kmail is a rock solid client.
Trojita – If I was to compare Trojita with any other email application, it would be with Claws Mail. While it feels a bit more modern in appearance, Trojita does offer some interesting functionality. For example, Trojita offers advanced network control. You can make sections for unlimited Internet, offline and "expensive" Internet.
Trojita is a solid choice for users wanting a decent IMAP email reading client. It's a KDE application, so you might think of it as a lighter version of Kmail.
What to look for in Linux email clients?
Finding the perfect email client for your Linux installation is a fairly personal experience. The key is to first think about which must have features are important. This means getting beyond the basics and considering secondary must haves. Do you still use POP email? Does the client also need to integrate with Exchange or other Web mail, without using IMAP? How about the ability to extended functionality beyond what's provided by default?
Once you have a handle on the stuff you simply must have, everything else is a secondary consideration. Appearance and overall feel are subjective stuff that can be overlooked if the core functionality is there for you.
What say you? Do you have an email client not listed that you simply can't live without? Let's hear about it, hit the Comments and share your favorite email client with the readers. Only use Web mail? That's fine too, tell us why in the comments below.