I've properly set up SPF and SRS. My mailserver is used to relay messages to different relayhosts (using sender_dependent_relayhost_maps) and postsrsd properly rewrites the envelope sender address to something like "srs0=xxx=yy=example.com=[email protected]" when doing so.

This works fine for most of the relayhosts, but some relayhosts do not accept such rewritten envelope sender addresses. Thus, I need to add the following variable in order to exclude such domains from the SRS rewriting:

target/postsrsd/postsrsd:
  ...
  SRS_EXCLUDE_DOMAINS=example.com
  ...

It would be great to add an environment variable so that such excluded domains could be controlled from my docker-compose.yml right away.