After migrate data from legacy system having mail in
mailbox format, domain mail usage statistics is not displayed under Home> Subscriptions> domain.tld -> <ail
The issue is in
maildirsize file which was not properly generated during conversion from
Maildir format. This file had created with zero values in it.
The workaround is either remove the
maildirsize file from the
/var/qmail/mailnames/domain.tld/mailbox/Maildir/ or set an appropriate mailbox limit for the subscription. Any of these actions will force system to recreate proper
maildirsize file, afterwards mailbox usage will start showing properly.