Having trouble adding your Gmail account to Mac OS X Mail software? It’s most likely an easy fix, as I found out today. On this particular Macintosh, they were running an older version of the operating system. Apparently, that version of Mac OS X Mail is not considered secure in the eyes of Gmail and they block access to it. Here’s how to fix it:
First, visit http://www.google.com/accounts/DisplayUnlockCaptcha and sign in with your Gmail username and password. If necessary, enter the letters in the distorted picture.
Secondly, and most important, visit this website: Allow less secure apps and choose “Allow” to let less secure apps access your Google account. This is a less secure option, but, it may be the only way to get your older Mail software to allow access to Gmail.