docker-mailserver: Cannot receive mail from docker host

Context

While I use this docker mailserver as a general mailserver for my domain, my docker host is also running a send only exim server to send me reports for other services. I would like to have that exim server send mails to my docker-mailserver, however the mails keep getting dropped.

The exim server can send mails to other providers just find, so there is no issue.

The first issue I could resolve by adding my (public) host ip to the mynetworks list in postfix However the logs of the docker container tell me that postfix tries to reconnect to the host (which cannot succeed) and the mail is never delivered. I added the host domain (which uses a different domain name) as well as the sending mailaddress to a hashmap referenced in smtpd_recipient_restrictions, however this did not change anything.

I suspect this is connected to a check to see if the sending mail address is valid, however I cannot seem to disable this check.

Expected Behavior

It should be possible to allow the host to send mail to the container

Actual Behavior

Any mailserver on the host is blocked by the container mailserver

Possible Fix

Steps to Reproduce

Your Environment

• Amount of RAM available: 6GB
• Mailserver version used: newest
• Docker version used: newest
• Environment settings relevant to the config:
• Any relevant stack traces (“Full trace” preferred):