I am really very sorry for you, but how do you think that the few details you gave in your opening post could give you any help?
No one but you knows your system and the configuration involved.
From your opening post, all you really read is:
- mailcow with Docker
- Reverse Proxy Apache
- Ubuntu 18.04
If it was already running, what did you change?
Anyone running a server on the net should at least be able to provide meaningful data to narrow down their problem. Otherwise, I would say goodbye to your own server, because that could quickly backfire.
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