4. Click on "Mailcow Server Information" below "Other integrations"
5. Create a new rule and fill in all mandatory information (Hostname, API Key)
6. Adjust all other options to your needs
7. Bind this rule to your Mailcow host object (e.g. via "Explicit hosts")
8. If you have no host object at all, create a dummy host for this (with no IP or something like 127.0.0.2)
9. Assure that your agents settings for this host object are correct (must contain "Configured API integrations")
10. Apply your changes
11. Execute a service discovery on your Mailcow host(s) and accept the newly detected services
12. Feel free to adjust the various parameters for thresholds within the available parameter sections (Setup, "Service monitoring rules" after searching for "Mailcow")