Someone, somehow created a new email account on my computer. And was generating spam from it. I caught it and disabled the account. A new one popped up within minutes. Then I change my email passwords, deleted the account and notified comcast.

"must have happened when we merged with time-warner"...

Since I've moved I'm no longer with comcast. But while I was, I'd periodically "manage my email accounts" to ensure no new accounts appeared.