Perhaps this little study will be helpful for others…

Goal:

Find a suitable replacement technology for email groups


Problem:

Popularity of Email groups is declining more than 5% per year 
Email servers are more expensive to run than web servers
Email is increasingly untrustable
- we want to register/authenticate users without using email
- we want push/pull notifications via mobile/desktop, rather than using email
Email is not very secure/private (eg. Gmail is thought to be data-mined)
Current tools like Mimerdesk, Qmail, EZ-mlm are very aged
- support is limited/non-existent
- compliance with spam prevention strategies is exhausted


What people don't appreciate in commercial solutions:

People do not like others data mining their conversations
People do not appreciate advertising (Facebook has gone from x% ads, to xx% ads in the last few years)
People do not want to be tracked
People do not like their privacy violated


Trends:

Mobile apps for keeping in touch of the latest news
- Instant notifications
- bonus feature: Offline replies, queued until reconnecting
Web-based access for desktop users (big screens)
Video conferencing
Federation - Friendica, Mastodon, etc (the Fediverse). Why interconnect? 
- when your node goes down, all your users and content are gone,
and from your perspective, the federation offered nothing.
- the federation offers discoverability (both ways), like free advertising for your node
- the federation may offer communication routing without using commercial relays (email, usenet, DNS)
- the federation exposes your walled garden to "bad neighbors", in addition to good
Cloud services
- how is privacy assured?


Content:

Styled text
Emoji
Pictures
Videos
Live messaging/broadcasts


Predecessor protocols:

SMTP
IRC
NNTP
HTTP
FidoNet (BBS era)


Social systems of interest:

Facebook. 
- every use is exploited
YouTube.


Popular Open Source Forums software supporting tapatalk mobile app - only Forum capability
phpBB - no wysiwyg, MBOX interface (1-2), not mobile friendly
- did not accept styled text (will not at all)
- BB means BBcode, and it's a real clumsy old-fashioned implementation
*MyBB - wysiwyg, no email/nntp interface, but can Merge another forum that DOES support mbox, Simplicity theme is mobile friendly
+ pasting styled text works great
+ plugin for HTML posting capability (benefit unknown): https://community.mybb.com/mods.php?action=view&pid=16
+ can upload image/movie to include in post (inline button during upload)
+ easily include youtube and pic URLs
- 86 character subject limit (+ auto-truncate)
O simple mobile app: https://github.com/0kzh/mybb-mobile (old/ugly, based on web browser)
+ symposium plugin stops email use for private messages
+ reputation system can block abusers from posting (req's plugin) 
Simple Machines Forum - wysiwyg, no email/nntp interface, not mobile friendly
- did not accept styled text in default setting (forced to plain)
- did not handle video link
- hit limits for pic and message sizes
FUDforum - wysiwyg, mbox, not mobile friendly, apparently no responsive theme, has been dying for years
- did not accept styled text in default setting (forced to plain)
- did not handle video link
- clumsy experience - took uploaded pic, but really didn't
Discourse - (not wysiwyg, side-x-side), mbox, moderately mobile friendly. Minima Dark seems ok-ish for mobile.
- mangled styled text in unwanted ways (suppressed bold text)
- does unexpected things with uploaded pictures and references to you tube videos
- seems ugly to me
bbPress - WordPress forum plugin
- Subject limited to 80 characters
- exposes WordPress to attack
- did not accept styled text in default setting (forced to plain)
- broken reply with pic and video links - did not resolve in main message
- cannot upload pics, etc
FluxBB - no wysiwyg, moderately mobile friendly, 
eg. Air, Earth, Fire and GrayOrange styles are responsive
- Subjects truncated to 71 chars
- pasting styled text results in unstyled text (no styled text editor - only BBcode)
- mangled styled text in unwanted ways
+ has a nice GPL app for Archlinux Forums Android: https://gitlab.com/Kanedias/archforums-android
- cannot upload pics, etc
- development is dead - they are joining up with Flarum
Flarum - no wysiwyg, moderately mobile friendly, startings of mbox interface (below)
+ mobile app for Android and iOS - Fluam (developed in China)
https://discuss.flarum.org/d/24291-a-flarum-native-client-for-android-ios-by-flutter/176
(on play store: Fla)
+ had notifications and MUCH more
- developer is completely starting over from scratch right now (after 3 month break)
- Subject limited to 80 characters
- did not accept styled text in default setting (forced to mangled, plain)
- no way to get proper message display from styled email
+ wysiwyg plugin: https://discuss.flarum.org/d/25590-true-markdown-wysiwyg
- adding an image/link is very cryptic
+ upload plugin: https://discuss.flarum.org/d/4154-friendsofflarum-upload-the-intelligent-file-attachment-extension
+ formatting plugin: https://discuss.flarum.org/d/17770-friendsofflarum-formatting
+ youtube link handled well
+ crude email interface: https://discuss.flarum.org/d/22855-wip-extension-mailbox
- You get two display modes:
1. takes up the whole screen to present "boxes" of unsorted forum names. 
2. basically twitter - another disorganized stream of talk
- large dependency set

Friendica [Fediverse] - simply too complex (and buggy) for the average user

Mastodon [Fediverse] - just another twitter
- like twitter, no Subjects
- 500 character limit to posts (can be changed via https://discourse.joinmastodon.org/t/howto-raise-the-character-limit/763)
- pasting styled text results in unstyled text
+ easily upload your local pics/videos
- URLs to pics/videos do not resolve in the message
+ nice mobile app (Tusky)
- very complex, large dependency set (worse than Flarum)
- not sure if/how Google indexes the content

BuddyBoss [commercial fork of bbPress] - WordPress forum plugin - appears more like Facebook than just a forum app
- Subject limited to 80 characters
- $$$$/yr - ongoing fees, due to wordpress upgrades and required updates
- exposes WordPress to attack
+ pasting styled text works great
+ pasted YouTube links resolve to clickable images automatically
+ allows local image upload easily in message
+ very nice mobile app
O referenced here as it sets a high bar for capability, for those who can afford it