Upgrade from older MKPs (before 2.1.0): If you upgrade from a already installed version before 2.1.0, you have to re-create your rules for the "Mailcow Server Information" (reason: parameter handling changes and migration to the new plugin API). HINT: It is a good idea to take a screenshot from all other Mailcow related rules as well.

Steps to accomplish this without problems:

Take a screenshot of your settings in the above mentioned ruleset Assure that you have access to the API keys you used within the current rules Delete all rules for "Mailcow Server Information" Install and enable the new MKP Re-create your rules with the previously saved information from steps 1 and 2 Apply your changes

General installation instructions:

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

How to create the API Key:

Login to your Mailcow instance with an administrative user
Got to "System|Configuration"
Take a note of the Section "API" and expand it
Within the section "Read-Only Access": 4.1 Activate the checkbox "Activate API" 4.2 Take care that the IP your CheckMK server ist listed in the input field "Allow API access from these IPs/CIDR network notations"
Save your changes and transfer the show API key to your CheckMK instance