All my email now gets SRS return paths in their header, only need/want this for one subdomain

[kees-closed]

I have lists.example.com which I use for lists which may forward mail to external domains. My example.com is only for internal mail delivery/forwarding, so that domain doesn't need SRS. Is there a way to only use SRS for mail sent to lists.example.com?

My mail server is setup as follows.

main.cf

sender_canonical_maps = tcp:localhost:10001
sender_canonical_classes = envelope_sender
recipient_canonical_maps = tcp:localhost:10002
recipient_canonical_classes = envelope_recipient, header_recipient

postsrsd (using version 1.10 on Debian 11), no other changes made.

SRS_DOMAIN=example.com

I know it doesn't harm to always do SRS. But I prefer to only apply it for where it's needed just to make troubleshooting easier in case there are issues.