# [...]

# Space separated list of plugins to load for all services. Plugins specific to
# IMAP, LDA, etc. are added to this list in their own .conf files.
mail_plugins = $mail_plugins quota


##
## IMAP specific settings
##

protocol imap {
  # Space separated list of plugins to load (default is global mail_plugins).
  mail_plugins = $mail_plugins imap_quota
}

# [...]