Some information about maildir++ that I have read: http://www.inter7.com/courierimap/README.maildirquota.html http://wiki2.dovecot.org/Quota/Maildir
When I have to deliver a message with an MDA I can use dovecot-lda.
If I have enabled "quota = maildir:User quota" I am pretty sure that in the mailbox on file system I find a file named "maildirsize"
maildirsize on top contain something like this "xxxxxxxxxxS" that specifies the SIZE quota in bytes.
LDA could delivery the message only when the SIZE written in mailbox is less than the SIZE defined by mail admin.
"Each member of the list consists of an integer followed by a letter, specifying the nature of the quota. Currently defined quota types are 'S' - total size of all messages, and 'C' - the maximum count of messages in the maildir. For example, 10000000S,1000C specifies a quota of 10,000,000 bytes or 1,000 messages, whichever comes first."
For this reason the value in bytes defined for the user must have S at the end.
At the moment quota-maildir.c contains a control for S or C so I can find this in log: Quota rule: root=User quota mailbox=* bytes=20971520 messages=0
But quota-util.c do not contains a control for C and S, so probably the support of maildir++ format is not complete.
Please let me know if I am wrong.
-- Ciao Mirko