Thanks for the suggestions. My ISP is Comcast. Not sure what you mean by SMTP, but I use Yahoo and subscribe to their POP3 service so I can download and send from Outlook.
Since it is my Yahoo address that is giving me problems, I presume there is no point in contacting Comcast -- they will point me to Yahoo. Also, changing my password might stop emails if my account were hacked, but it would have no affect if someone were simply using my email address, correct? Also, it does not appear that chaning my password would help my emails to be sent and not bounce back.
Am I understanding your suggestions correctly? Thanks!
Jenn