Our default Postfix configuration can easily be extended to add parameters or modify existing ones by providing a
docker-data/dms/config/postfix-main.cf. This file uses the same format as Postfix
main.cf does (See official docs for all parameters and syntax rules).
One can easily increase the backwards-compatibility level and set new Postscreen options:
# increase the compatibility level from 2 (default) to 3
compatibility_level = 3
# set a threshold value for Spam detection
postscreen_dnsbl_threshold = 4
How are your changes applied?
The custom configuration you supply is appended to the default configuration located at
/etc/postfix/main.cf, and then
postconf -nf is run to remove earlier duplicate entries that have since been replaced. This happens early during container startup before Postfix is started.
Similarly, it is possible to add a custom
docker-data/dms/config/postfix-master.cf file that will override the standard
master.cf. Note: Each line in this file will be passed to
postconf -P, i.e. the file is not appended as a whole to
docker-data/dms/config/postfix-main.cf! The expected format is
<service_name>/<type>/<parameter>, for example:
# adjust the submission "reject_unlisted_recipient" option
There should be no space between the parameter and the value.
postconf -Mf in the container without arguments to see the active master options.