But what can you do? You can't police the messages for every potential form of abuse. (I've only ran an automated spam filter to make sure that the service is never used for blatant spam. I've also blanket-blocked some domains whenever I noticed a pattern in any abuse reports, and finally recipients were able to easily do a permanent block themselves). In any case, running a messaging service even more difficult if you're a small guy and not Facebook or Google.
I've added more information about the details of the suspension in another post on here: https://news.ycombinator.com/item?id=24998922