I have seen it happen a few times: a user is contacted and suspended for rude or offensive behavior and they respond to the moderator message with even more rude or offensive language. Example:
I'm writing to explain that your account has been suspended for 1 week for rude behavior. Please refrain from engaging with users in a hostile tone in the future.
You're a worthless piece of garbage and don't know the first thing about moderating. I've moderated many sites before and you don't know diddly squat about how to handle a community. I hope you're proud of yourself for satisfying your Napoleon complex. Delete my account if you want I don't care, this place stinks!
Use your imagination for actual offensive language.
This seems to be a very common pattern when these types of mod messages are sent out. Should I just ignore these types of messages or should they be compounded into further punishment?