I set up Postfix under Debian Wheezy with MySQL and virtual users using this tutorial. Thunderbird is recently giving me alerts "You exceeded your mail quota" and saving/moving emails is denied. The user I have set up in the users table in MySQL has a quota set to 0 (Zero). I would think the user has no quota.
I was experiencing the same under Debian Squeeze with a similar setup. In my current Wheezy setup, I actually omitted the quoata patch from the tutorial, to hopefully avoid this issue. I do not see any configuration anywhere that could possibly be overriding the MySQL user quota of 0. I am pretty sure I tried setting the quota to NULL with the same result. Instead of setting a really high quota, I would like to disable the quota alltogether.
BTW, an excerpt from my /etc/postfix/main.cf
mailbox_size_limit = 0
Update, I am using Courier as the mail delivery agent and I have noticed the following file which might be setting the quota?:
I haven't trusted myself yet in editing or deleting this file.