Count quota

(Requires Dovecot v2.2.19+)

The quota is tracked internally within Dovecot's index files. Each mailbox's quota is tracked separately and when the current quota usage is wanted to be known, the mailboxes' quotas are summed up together. To get the best performance mailbox list indexes should be enabled.

WARNING: If you're switching from some other quota backend to count, make sure that all the mails have their virtual sizes already indexed. Otherwise there may be a significant performance hit when Dovecot starts opening all the mails to get their sizes. You can help to avoid this by accessing the mailbox vsizes for all the users before doing the configuration change: doveadm mailbox status -u user@domain vsize '*'

Configuration

mailbox_list_index = yes
plugin {
  # 10MB quota limit
  quota = count:User quota
  quota_rule = *:storage=10M

  # This is required - it uses "virtual sizes" rather than "physical sizes" for quota counting:
  quota_vsizes = yes
}