I love using GMAIL because of google drive. Just set up a GMAIL business email address firstname.lastname@example.org (not the exact words lol) and trying to set up MAIL to work with this. I already have this setup with a different business/different email address and it works. I click on settings or "CMD+," - click on ACCOUNTS, hit the little + sign bottom left corner, hit GOOGLE. Under my name I enter the details (email@example.com) followed by password and WHEN I HIT ENTER/SUBMIT, ALL THAT INFORMATION DISAPPEARS!