Extract instances domain

What i need:
A processing step which extracts the users instances (changed from domain).
I.e. https://XYZ.onedata.de → XYZ

Background:
We run several domains, one for development, one for testing, one for training, prod etc…
Some users have accounts on both training and production. And we have a reminder functionality.
Problem: The user receives a reminder email and does not now from which instance.
Solution:
Hence, what i need: a method to send the email from:

"messages?from=noreply@$instance$.onelogic.de&to="

Where i want to extract

$instance$

in its own processor step.

Are you talking about ONE DATA domains, or about several instances? The XYZ.onedata.de part looks like it’s actually several instances, rather than several domains on one instance.

An idea that works for both cases: Define a central Data Table (“Meta-Table”) with instance/domain wide constants (such as the instance/domain identifier), and this can be loaded in all workflows as needed.

This Data Table should exist on all instances/domains and have the same entries, but different values. If you often export/import the project, you can create a separate “static” project that remains does not contain any logic but only instance-specific configuration data. Then you only export/import the other projects, but the static project remains always stays the same and the necessary Data Tables are shared into the other project.

Thank You Marco!
This should work.
Even though it is not really the dynamic solution i have hoped for…

Unfortunately, there is no system variable for the domain name (yet), that would be the “perfect” solution.