I have been a dreamhost customer for 3.5 years, and have had this email address all that time.
I have two support tickets open at the moment, and they have been for 7 & 8 hours, but still no reply.
I know the usual target is 24 hours but this is an urgent issue, has been marked as such, and I normally get responses within a hour or so.
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The mail system
[censored]@jazzle.co.uk: User unknown in virtual alias table
Final-Recipient: rfc822; [censored]@jazzle.co.uk
Diagnostic-Code: X-Postfix; User unknown in virtual alias table