I have had forums on this site for a couple of years; nobody used them except spammers, although they had to register an account with an email to post there.
Today I decided to delete all those posts, and the forums, and disable the forum module, and block all the users I did not recognize. I automatically sent an email to the blocked accounts so they would have a chance to ask me to reactivate them before they were deleted in a couple of weeks:
We are removing spammers at netsperience 2.x
Your account on netsperience 2.x has been blocked.
Let us know if you are not a spammer and want us to reactivate
your account. After a while, we will delete all blocked accounts.
-- netsperience 2.x admin
If you have a Drupal site with forums enabled but you don't really use them, you may be surprised what a spam farm you are hosting!
I received this response from a blocked account, from someone who clearly did not remember registering:
eck i have no idea of what netexperince is!?????