Postfix error - cyrus problem

[Daniel Schulz]

Hello,

I'v read in google, that this error is not the problem from postfix, 
but rather from cyrus:

---------------------------------------------------------
The Postfix program

<MAILBOX at domain.net>: data format error. Command output: MAILBOX:
Mailbox does not exist
---------------------------------------------------------

does anyone know, what that means? I haven't found a answer on this
error.

Daniel