From the FAQs "We do this for fun and get hundreds of mails a day so we can't respond personally to questions about the site or your account."
If the block was for a message you sent then this will be temporary and lifts after a few hours.
There would have been a pop up that states:
"To protect our users from SPAM or UNWELCOME CONTENT, because your message contained a WEB SITE or UNWELCOME CONTENT it has been blocked. This is to protect people like you from receiving spam! PS. please don't try and get around the blocks or your account will be removed"
