This may sound a bit complicated but I have quite simple intentions for it!
Lets say I have a catchall email address for a domain. Is it possible to query all of the posts in that email account using imap (or something like that) and put the emails into the messages section of the buddypress powered site.
This way, if a user who has an account at my site (schoeben.com) had a username like spencer, then, any email that was sent to firstname.lastname@example.org would end up in the catchall account but it would still be marked as adressed to email@example.com.
Then, could you somehow query the catchall account and find any emails that are addressed to (*username*)@schoeben.com and put those messages in with the rest of the internal buddypress messages for (*username*).
Anyway, just looking to be pointed in the right direction.