Hi,
I got the error in the subject by trying to start the MTA.
The same error is discussed in the following topics:
https://lists.ciphermail.com/pipermail/users/2016-December/003376.html
https://lists.ciphermail.com/pipermail/users/2016-August/003347.html
I'm not that familiar with docker.
Thank you for your support!
Max