I have friend why asked for my help. He is getting lots of 'returned' emails, indicating emails which he didn't send could not be delivered. They are all taken from his contacts list.
He's recently changed the password and there are no signs of the email in his sent items.
Any tips as to how I can get the bottom of this? I would have guessed that this is spoofing however the fact that they all are being sent to people on his contact list suggest otherwise?