Allow you to add like reactions as FB (like, haha, wow, love, sad, angry, ...)
Route emails between Odoo systems
Restrict save as new template button from the send email wizard
Show (and search) External ID in list and form views of Mail templates.
Universally manage and style mail templates sent from Odoo
Fix mail templates for multilingual
Tracking Duration When changing status (selection field) just like many2one field (stage_id) on CRM app
Modern presentation of the messages of your discussion
Mail/Message Related Source Document Link
Show avatar when mentioned.
Message Template for Send Message on Chatter
Chatter as history attachments
Search and filter messages in Discuss app
Multi Company Support of Scheduled Activities
Allow to Select All companies on Single Click
Support multilingual for tracking on records