The official Dovecot wiki should be your go to for setting up mail quotas, but here I am describing how I setup mail-user specific quotas to work with my LDAP environment.
I included a quota configuration for
user_attrs in my
dovecot-ldap.conf.ext consisting of the following
user_attrs = mailHomeDirectory=home,mailStorageDirectory=mail,mailUidNumber=uid,mailGidNumber=gid,mailQuota=quota_rule=*:bytes=%$
The quota limit is in the mailQuota field:
Once Dovecot has been restarted with the above quota limit, we can then add the
mailQuota attribute with a value using a preferred metric unit. For example, a mail user record might have a quota limit of 250 MB.
The above quota is user-specific so this will end up overriding the global quota.
I use a lot of aliases to save time, so putting this in your user profile is recommended.
alias quota='doveadm quota get -u $1 '
$ quota johndoe Quota name Type Value Limit % User quota STORAGE 0 256000 0 User quota MESSAGE 0 - 0
See the doveadm-quota wiki for additional options.