Funny thing, PayPal is lobbying by the e-mail providers to ban unsigned emails. This could stop phishing, which is one of PayPals biggest soar spots.

Network world writes:

"So far, no agreements have been reached, but the idea is one that PayPal would like to see from other e-commerce businesses, said Joseph E. Sullivan, PayPal's associate general counsel, at the International E-Crime Congress in London.
An agreement with, for example, Google for its Gmail service could potentially stop spam messages that look legitimate and bypass spam filters."

Although I'm all for security and putting an end to spam, phishing, viruses etc., it seems to me that PayPal is looking for an easy way out of the whole ordeal.

Instead of putting real effort into making its own site more secure, securing its own mail and really checking out who the hell is signing up for accounts, logging in and doing the transactions (try learning from Moneybookers, lazy), PayPal is taking a leaf out of the almighty eBay's book - the resort of so many scammers, liars and fake goods salespeople.