In case someone wants to try: http://hg.dovecot.org/dovecot-2.2/rev/0a08efeb3f40 The commit message lists the TODO. So for example if you want to enable it just for webmail (because quota limits aren?t there yet): mail_attribute_dict = file:%h/dovecot-attributes local 10.0.0.0/24 { imap_metadata = yes } Compared to the old metadata plugin, there are some improvements: - Uses lib-storage attributes internally, which means: - dsync replicates METADATA - it will be easy to add support for untagged METADATA notifications to clients when they change - SETMETADATA atomically either updates all or none of the changes Things that work in the METADATA code, but still require lib-dict changes to work properly: - Values with unlimited sizes - Values with binary data (NULs)