1. Roundcube
Roundcube has been around for more than 10 years, and it has since then established itself as a modern email client whose most prominent feature is the pervasive use of AJAX technology. Written in PHP, Roundcube can be easily deployed in conjunction with a LAMP stack or any of its variations that support the PHP programming language.
Roundcube is free, open source, and available in over 70 languages. It features sophisticated privacy protection mechanisms, comes with a full-featured address book with groups and LDAP connectors, canned response templates, a template system for custom skins, and it can be extended with third-party plugins.
If there is something about Roundcube that deserves criticism, it has to be the outdated look of its interface. Whereas Gmail, Outlook, and other popular email services have significantly improved their user experience, Roundcube stayed mostly the same. Some Roundcube users, however, like this because not having to re-learn how to use the client every now and then allows them to be more productive.
2. Rainloop
If you’d prefer a straightforward alternative to Gmail, with modern user interface design, complete support of IMAP and SMTP protocols including SSL and STARTTLS, and integrations with popular social media sites and cloud file storage services, Rainloop seems like the perfect choice.
Written primarily in PHP and licensed under the GNU Affero General Public License, Rainloop is simple to install and upgrade, has modest system requirements, and doesn’t require any database to work, except for contacts. Found among its many features are client-side OpenPGP encryption, keyboard shortcuts, and plugin support.
Unfortunately, Rainloop doesn’t have the largest user base, and its documentation leaves something to be desired. Even the installation instructions should be more detailed to help less experienced users make Rainloop their detail email client.
3. Mailpile
Mailpile started in 2014 as a response to Edward Snowden’s 2013 disclosures, which revealed numerous global surveillance programs, many of them run by the NSA and the Five Eyes Intelligence Alliance with the cooperation of telecommunication companies and European governments.
Mailpile can be easily installed on just about any device—from your laptop to the Raspberry Pi. Because Mailpile is supported entirely by donations, there are not intrusive and potentially dangerous ads to worry about, and your privacy is protected at all times using state-of-the-art encryption.
Even when the people behind Mailpile were just putting together a list of features the client should have, they already knew that Mailpile must perform better than popular email services in order to be attractive. It’s now clear that they’ve succeeded in achieving their goal and created what might just be the snappiest email client ever.
4. Squirrelmail
Initially released in 1999, Squirrelmail has been around for a very, very long time. Because it’s been around for so long and developed so conservatively, it falls behind all other email clients on this list in terms of its design and user experience.
There are, however, several good reasons why so many organizations still swear by Squirrelmail: it’s available for any platform supporting PHP, including Linux, FreeBSD, macOS, and the server variants of Microsoft Windows, and there are over 200 third-party plugins available for download from the SquirrelMail website that extend the client’s functionality.
If you’re looking for an email client that just works and likely doesn’t have any major security flaws, Squirrelmail is still just as good of a choice as it was when it was first released nearly two decades ago.
5. Horde Mail
Horde Mail is an email client belonging to the Horde groupware, which rests on the Horde framework. The purpose of the framework is to provide all the elements required for rapid web application development of standards-based applications capable of using existing platforms and backends.
Other applications that rely on the Horde framework include Ingo (an email filter rules manager), Sork (a collection of four account management modules), Kronolith (a calendar application), Mnemo (a note manager), Nag (a multiuser task list manager), Turba (a contact manager), and several others.
Horde Mail supports IMAP, POP3, and SMTP protocols, has native PGP encryption, comes with a WYSIWYG HTML editor for composing messages, and can download multiple attachments as a single ZIP file, just to name a few of its features.
How to Install and Configure Roundcube
In this section, we go through a very basic set up of Roundcube to give you an idea of what it involves. Our instructions are by no means meant as a replacement for the official installation guide, which is far more comprehensive. Before you begin, you should also verify that you meet all the requirements to avoid running into easily avoidable problems.
1. Download Roundcube
The first step is to download Roundcube from its official website. We recommend the Complete package as it contains all dependent packages. Roundcube is distributed as a .tar.gz file, and it’s necessary to extract it using your archive manager of choice.
2. Upload Roundcube to Your Web Server
Connect to your web server using your favorite scp or FTP program and upload the extracted files to it. The temp and logs directories must be writable.
3. Create a Database
Roundcube needs a database to work, and it supports multiple database backends, including MySQL, PostgreSQL, and SQLite.
4. Configure PHP
To work properly, Roundcube requires certain specific PHP settings. The bare minimum includes:
- Memory limit: memory_limit=64M,
- Options that control logging: display_errors=Off, log_errors=On, error_log=logs/errors.log,
- Options that control file uploads (e.g. max attachment size): upload_max_filesize=5M, post_max_size=6M,
- Options that are not compatible with Roundcube: zlib.output_compression=Off, suhosin.session.encrypt=Off, session.auto_start=Off,
- Options that control session behaviour: session.gc_maxlifetime=21600, session.gc_divisor=500, session.gc_probability=1.
Web administrators often forget about one or more of these settings, which then leads to annoying error messages.
5. Configure Roundcube
Finally, it’s time to finish your installation by visiting http://your_server_ip_or_domain/installer and following the instructions. Roundcube configuration is a complex topic as the email client has over 200 configuration options, which is why you should check this page to learn more about it.
