Unable to transfer due to mailbox bug


I am trying to transfer my character Tzakeja, Golemag EU - to Ashbringer EU using the free transfer service.

For some reason it is telling me that it cannot do it due to an error - the mailbox has mail and I must clear it before transfering.

I don’t have any mail in that inbox at all, I have deleted all old mail, yet the problem persists.

Please help!