Freewill,
I think that Ts shouldn't have to take abusive behavior that has crossed their boundaries, and every T has a different threshold. Of course, Ts need to realize that "abusive" language can be transference and an excellent opportunity to get to the root of problems.

Ts should make that clear at the beginning or let you know after you cross a boundary. It's a good opportunity to teach you how to express yourself in an appropriate manner.

I emailed my T some angry messages that were quite vindictive, which is really not like me at all. I was going through a difficult time and he was triggering me all over the place. He solved it by telling me that he was no longer reading my emails. I think he would have been more aggressive if I had been doing it in session.