Can't Faction Change - Mail Issue

I'm trying to faction change from Alliance to Horde, but when I try to do it I get this error. A character cannot change factions while there is mail in their mailbox or en route to their mailbox.... I have checked multiple times over the past few hours and I have no mail. Please help.

I also opened a ticket in-game. Still waiting on a response.

Name: Darkcraze
Realm: Kalecgos