Yes, definately. I can see losing your account quickly by trying to do so... Click Fraud would be one.
There is no way that Google would allow Adsense in sigs. If you want to know for sure, however, why don't you just email Adsense and ask?
Nobody is talking about email signatures.. Anyway a safe way would be a form field where you input your AdSense Publisher ID and then your signature gets an AdSense block, everything done automatically.
Jesus Christ, are you dense? There should be an IQ test before people get an Adsense account. Goodness sakes.
I think it would eradicate Adsense and the credibility of the Adsense program, thats why it wont be allowed by Google
if everybody started to do it there would be about 30 ads per page which would be against Google TOS. got from a site on my Gmail account. Last I checked with Google about Adsense in email, they said it is against TOS.