when i used this domain rulein "Personal leads" rule under "see own leads" group, so that users can also see those leads that they follow with leads they own i got an error,
domai rule :
['|',('user_id','=',user.id),('user_id','=',user.message_follower_ids)]
error:
"Invalid value %r in domain term %r" % (right, leaf)
AssertionError: Invalid value mail.followers(10,) in domain term ('user_id', '=', mail.followers(10,))
Edit You should search with the current user's partner in the models followers, like:
['|', ('user_id', '=', user.id), ('message_partner_ids', 'in', [user.partner_id.id])]
Interesting example is one of Odoos default rules for project tasks "Project/Task: portal users: (portal and colleagues following) or (followers and following)"