Mail functionality in WikiSuite is handled as follows:
- Cyrus IMAP
- Cypht, a webmail client which is integrated in Tiki Wiki CMS Groupware (starting in Tiki20)
- SabreDAV for CalDAV and CardDAV support.
Please see general component criteria and the other Software Components for WikiSuite.
Why Cyrus IMAP and Cypht instead of the many options in this space? Very good question. One important reason: JMAP!
Why Cyrus IMAP
- JMAP support
- Very active development
- Fantastic community and leadership, and weekly community meetings
- Longevity: started in 1993!
Why Cypht
- Written in PHP
- Jason Munro, the Lead developer, is doing a fantastic job with the project
- Available on Packagist
- Lots of features
- JMAP support
- Manage multiple email accounts in a unified interface
- Cypht accepted to change its license for easy integration into Tiki: https://github.com/cypht-org/cypht/issues/333
Why not Roundcube
- Roundcube is a fantastic webmail and we used for a while as part of Kolab but
- No JMAP: https://github.com/roundcube/roundcubemail/issues/5918
- No way to aggregate email: https://github.com/roundcube/roundcubemail/issues/4972
- While it's in PHP, there is no way to get via Composer/Packagist: https://github.com/roundcube/roundcubemail/issues/5938
Why not Kolab
- Kolab is a great standalone mail stack suite. Kolab was the mail stack component in WikiSuite for the first few years, but it was too much work to integrate tightly and thus, it stayed quite standalone from the rest of WikiSuite. So we moved to a more tightly integrated solution.
- Kolab uses Roundcube, which doesn't support JMAP
Why not Apache James
- Apache James supports JMAP so it could have worked, but it would be too much work to integrate nicely. WikiSuite congratulates and thanks the Apache James project for their support of the JMAP standard.
Why not SOGo
SOGo is a very interesting solution, and was a strong candidate. However, no JMAP support, and it would have not been as tightly integrated as the chosen solution. SOGo is written in Objective-C (vs Cypht in PHP)
Why not Dovecot
Why not Zimbra
- Zimbra is partially Open Source: https://www.zimbra.com/legal/licensing/
- The Zeta Alliance is trying to improve this: https://zetalliance.org/the-zeta-alliance-charter/, a bit like like situation with the OCA with Odoo
- As of 2020-01, no support for JMAP: https://jmap.io/software.html#servers
- https://en.wikipedia.org/wiki/Zimbra 5 owners in 14 years is a little worrisome
Why not Bluemind
Email required to download. "A valid email address is mandatory, we will send you a download link along with instructions."
Why not Zarafa / Kopano
Zarafa was an interesting solution, but it wasn't really Open Source. It was forked to Kopano, which should be better. Let's keep informed of their progress 
Why not Horde
Horde is a fully Open Source solution that has been around for a long time. And goes beyond just email with many other apps, including a wiki. And it works with Cyrus IMAP. This is a good solution. However, in the context of WikiSuite, we'll end up with a more integrated solution on our chosen path.
- As of 2020-01, no support for JMAP: https://jmap.io/software.html#servers
Why not EGroupware
Why not Group Office
- It supports JMAP. Congrats!
- But not fully Open Source. Features are split between the Open Source Community edition and the proprietary Professional editions, along with Separate Add-ons
- https://www.group-office.com/
Why not SquirrelMail
SquirrelMail was a popular webmail a while back, but it hasn't kept up with the times.
Why not OBM
The team behind OBM has stopped developing it, and are focused on Apache James and OpenPaaS
Why not Thunderbird
Thunderbird is a desktop application. It can be used with WikiSuite by connecting via IMAP. However, we need a web-based solution as the main solution.
Why not Claws Mail
Claws Mail is a desktop application. It can be used with WikiSuite by connecting via IMAP. However, we need a web-based solution as the main solution.
Why not Gmail
- Not Open Source
- https://mako.cc/copyrighteous/google-has-most-of-my-email-because-it-has-all-of-yours
Why not Office 365
- Not Open Source
(to do: add all the other options)