Someone used my email account?

Someone used my email account to send out spam to all my contacts. It does not appear in my sent box. I found out because I had some old addresses in my contacts and I received a MAILER-DAEMON@ failure notice for each of the bad ones. I ran a malware application which found quite a few problems which my McAfee security program did not detect. I then changed my Yahoo password. I then set up a Sign - in Seal and changed my password again. Currently advising my contacts (not one came back to me to ask why I'd sent this spam, but they did receive it) to do the same as I have done. Anything further I can do?