We are soon making a change so that all mail sent to staff and other clearanced accounts will require a subject.  We are giving you advance notice so you can get in the habit now so that you don't accidentally just hit send and them browse away not noticing the erorr and assuming the mail is sent.

Sooo... mailing an account that has clearance, have a subject :)

I can't exactly say House is Staff, but, it has clearance.  So for example, if you mailed house without a subject, the mail would error.

My sons account, while never actually played the game and not really staff, has access to vote site records and can give out credit discount codes, so if you mailed that account it would require a subject or the mail would error.

Clearance = Any account that has higher than player access in any capacity.