Paid Realm Transfer Failed But No Mail In Box

I attempted a paid realm transfer with this character in order to follow some friends who did the same. When I attempted to transfer, however, it said that it failed due to having mail in the inbox. I logged back on and checked and the character has no mail in the inbox. It has been this way for a day now so I am certain if I had any inbound mail or quest mails incoming they would have already arrived. Are there some sort of hidden mails I cannot see that is blocking me from transferring? Thank you in advance.