I got this tip from @Chem
Use case:
When a certain task is finished the status field gets changed to finished.
Upon submitting the form change I wanted to email an interested person.
So you invoke an email by setting a condition where the status of this task is set to “finished” in the component content itself - all standard.
Problem:
Every time I submit the form after this action, an email will be sent. I just want to send the email once.
Solution:
Put in a flag field in the data table, which you activate with a rule when you submit the first email, and you check for this activated flag field every time the form is submitted, so to prevent sending another mail.
I hope this helps others with the same question.