1) Since Dovecot 2.x, quota rules are by default in bytes, and not in kilobytes (hence multiplicating with 1024 is not going to be megabytes). Fixed this by adding 'M' suffix. 2) Since Dovecot 2.x, the quota rule is always named `quota_rule` or (for userdb prefetch) `userdb_quota_rule` (there were some incorrect namings in the distribution configs). Ref: http://wiki2.dovecot.org/Quota/Configuration#MySQL