Is there any way for a banned user to check their conversations? I've had issues where users get banned because they've hit too many warning points, but have email notifications disabled and then aren't able to see to warning conversation message to see why they got banned.
It makes things confusing for both the users and moderators as it creates communication issues when a banned user can't view their inbox.
Theoretically you could override the _assertNotBanned() function from XenForo_ControllerPublic_Abstract in XenForo_ControllerPublic_Conversation thereby allowing banned users access to conversations. It requires custom programming and testing to make sure it's working like you want.