Changes on butler dates command?

[Tomas Dreves]

Im trying to generate this command (ive made a long time ago):

*when anyone enters a card description containing a date after "Desired delivery date:", set due on the date and remove the matched text"*

But i cant figure out where is the trigger command.

What i want is being able to set a due date on an generated card via Email. But i cant find the trigger that detects dates on the body of an email.

Any suggestions?