Email delivered to wrong mailbox

[#1]

I have an alias for postmaster to one of my mailboxes. Emails from Plusnet sent to postmaster have been delivered to the correct mailbox for years.
Today I received an email in my catch all from Plusnet which was sent to postmaster (header contains Envelope-to: postmaster@xxx.plus.com).
Anyone else seeing similar problems?

[#2]

This redirect still works for me.
I've just sent a postmaster@ message from an external account and it ended up in the correct redirected (F9) mailbox not my catch-all.

[#3]

@jelv, the maildb has no entry for 'postmaster' despite it being visible via the Manage My Mail interface. I've set a script running to rebuild your mail account however this may take a number of hours to complete given the number of mail entities you have set up.

[#4]

Strange! Last months billing notification went to the right place so I wonder what has happened in the meantime?
Edit: Not so worrying for me as I still received the email. But for anyone who has the catch all turned off the loss of maildb entries is rather more concerning!