That's a Yahoo setting which I just Googled: http://help.yahoo.com/l/us/yahoo/mail/yahoomail/tools/tools-84.html
You could probably alter the settings by clicking Options, seen at the top right of your picture.
That was it, removed check mark in options. AT&T wanted $129 for this answer
Thanks for help. - Tom66
Crikey, good job you posted here then...LOL!!