"Target is unfriendly" when mailing, part 2.

I'm trying to send mail from my horde DK Batista to my horde priest Miasma, and it's saying "Target is unfriendly". Any way to fix this that won't cost $$? I've faction transfered and server transfered these characters multiple times, so I don't really know who is 'supposed' to be horde or alliance, from the mail system's point of view.

Is there some way someone can flip a switch on my horde priest to say "this character is horde"? Currently, it seems like, in spite of being undead, the mail system is considering the character quasi-alliance.

Realm: Emerald Dream
Character: Mïasma (Alt + 0239 for the ï)