I cannot explain it either. It just goes without saying that this is an unusual event perpetratied by someone who enjoys what he is doing far to much.
I did not know that it was so easy to "steal" someones email account and send out emails under that assumed identity. I guess it is more common now a days than it was in the past.
The mail was sent from that email address, the account owner has a record of it, but has proven sufficently enough to me that it was not him who had sent it.
I guess the guy new or guessed the password used for the account. Or more likely he used a password getting program and this guys account was just one of many that he has uncovered passwords for.
I change all of my passwords sometime ago following the virus attacks from eariler this year. (Just in case)
The chances of someone guessing or obtaining my passwords is equal to any one else given the right program and security precautions. So if it can happen at yahoo, it can happen anywhere. Just and FYI.