[Dovecot] Dovecot+Postfix+Mysql+quotas doesn't work

[ben at electricembers.net]

>> In my webmail, he informs me that I'm using the percentage of quota. But I
>> can't make the TRASH folder is ignored. That is, I can't put a higher
>> limit on it than the others.
>> Am I doing something wrong?

We use something like this in our "user_query" SQL, which overrides the 
rules put in config file(s):

  concat('*:bytes=', quota) AS quota_rule, 'INBOX.Trash:ignore' AS 
quota_rule2, 'INBOX.Spam:ignore' AS quota_rule3, 'INBOX.Virus:ignore' AS 
quota_rule4,

But we run version 2.0.9 - quota stuff changed a bit from 1 to 2.
(I think I had to add the "INBOX." part.)

>> Another thing. I'm not receiving message of quota exceeded. This is with
>> the MTA or dovecot?

That is another thing. Likely a bit different in Dovecot 2 now, but in any 
version, only the LDA knows when the theshold is being crossed @ deliver 
time. Dovecot's LDA can be configured to execute a script which must do 
the actual delivering of the warning message. Example script given in 
documentation is working for us.