Data format error: : Mailbox doesn't exist

[Henrique de Moraes Holschuh]

It looks like you are using my Debian packages, no?  Please read the docs in
/usr/share/doc/cyrus21-common/, they explain everything.

I'd guess that your postfix "cyrus" transport is that broken crap using the
pipe transport and the deliver/cyrdeliver script that comes in
/etc/postfix/master.cf by default?   If it is, switch to direct lmtp
delivery from postfix to Cyrus.

If you still can't get it to work, file a bug in the Debian BTS (use the
reportbug package and reportbug command).  Make sure to include the full
postfix configuration (master.cf and main.cf), because there is where the
problem is.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh