Noutro forum:
Log in to your Facebook account
Go to this page:
https://www.facebook.com/help/contact/571927962827151 Copy and paste somethink like:
Dear Facebook Team,
it seems that you blocked the domain XXXXX.comfor no obvious reason and i want to ask you to unblock it after you have checked it and think its safe.
Thank you very much!
Yours,
xx