Sure, Dennis.....a few ideas....
Mac Mail has a built in connection doctor, run that... if something's wrong the light will be red rather than green, and clicking on the area with the red light might tell you something. Also the Default email protocol for Mac Mac is IMAP rather than POP. You may have to go into Mail, then Preferences, then server settings and use the same ones that are on your phone. If your ISP (internet service provider) has a web site/web page, most of them do....there should be a section there under support, then email, and the correct email settings should be listed there, including what port settings to use and if TLS/SSL should be on or not, and various other important things
well, that's all I have for today
jon b