Hi,
I can’t use the free transfer service due to “Please clear the mail from this character’s mailbox” error, which has been addressed. There are no items in my mailbox, which I cleared it like 12h ago. My ticket will be answered in 6 days…
What do I do ?
Delete all the people from your ignore list.
If you have ignored someone, and they sent you a mail, you won’t see that mail, but it will still be there. So you need to unignore everyone, then check your mailbox again.
Cool, I never thought of that. The problem still remains, because I have not ignored anyone.
You may have done a quest which results in a mail arriving afterwards - some are up to a week later, which messes up the empty mailbox. If it’s not that, hopefully your ticket will be answered soon. If you’ve put it in the right category, it’s something I think they can fix fairly quickly so may get to you sooner than it says.
This was the first thing that came to mind as well. While you can’t see the mail it is technically in the characters mailbox pending delivery and would block a character transfer as a result.
If you’ve already sent in a ticket the Support team will be able to check if that is the case. In the meantime keep an eye on the mailbox to see if anything pops up 
I have same problem i make 1 ticket about 3 days ago I still haven’t gotten a response from blizzard this game is getting worse the support of the worst I’ve seen so far
Did you read any of the other threads about this issue? Some of them have work-arounds, which yes require a bit of effort on your behalf, but its better than waiting 16 days for your ticket to be answered.
what can i do but i’ve seen the email more than 1000 times i don’t have sales no oh i don’t have anyone on the ignore list i don’t have any complete quests to deliver i don’t know what to do but i’m running out of patience