check_policy_service sends size=0

[dovecot at ptld.com]

> if that is entirely done in the postfix side dovecot could be stopped
> and it will still work on the postfix side of it, if dovecot policy
> service is down, postfix will not get the result from it, but it could
> failback to check dovecot dict still with is used in postfixadmin,


I think the issue is performance. Dovecot uses index files to store 
mailbox size instead of hitting the OS file system to compute size each 
lookup. Postfix doesn't read these index files and the postfix author 
will never add that code to postfix, because dovecot already does it. 
That is the whole reason why there is check policy service.

As of now you can write your own policy service script to ask the OS for 
the collective file sizes of the users directory and you wont need 
dovecot, but you will suffer performance on a busy server.