Who on Nostr: Ever wonder why emails come with a line at the end saying "sent from my iPad" or ...

Ever wonder why emails come with a line at the end saying "sent from my iPad" or "sent from proton secure email" etc?
Just suppose it's an encryption hook? Put there in case needed to access our messages one day...
Remember how the Enigma Code was cracked - somebody realised all German messages ended "Heil Hitler".
No idea if I'm right about this, but I always delete those phrases before I send an email.