[BlueOnyx:24031] Sendmail refusing to accept message

[Greggk]

Hello,
My setup is that I have a barracuda server filtering all my email before
getting to the BO server.
Everything works fine, however someone recently alerted me that their email
is not going through. After some checking I can see that from the barracuda
it delivers it to the server, but as soon as it reaches the server I get
the following error: mailer=local, pri=24392260, dsn=5.0.0, stat=Can't
create output

This is happening only to one email address. Somehow the server doesn't
like this person? :)
I have tried everything I can think of to figure this out. I have disabled
the black lists from the apf firewall, but I get the same exact error.
Any thoughts?
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