dovecot/templates/default/conf.d/auth-checkpassword.conf.ext.erb

# Authentication for checkpassword users. Included from auth.conf.
#
# <doc/wiki/AuthDatabase.CheckPassword.txt>

passdb {
  driver = checkpassword
  args = /usr/bin/checkpassword
}

# passdb lookup should return also userdb info
userdb {
  driver = prefetch
}

# Standard checkpassword doesn't support direct userdb lookups.
# If you need checkpassword userdb, the checkpassword must support
# Dovecot-specific extensions.
#userdb {
#  driver = checkpassword
#  args = /usr/bin/checkpassword
#}