Platinum Product Expert
bkennelly
3/27/19
Recommended Answer
"Less secure" means that the program only supports plain password authentication, not OAuth2. Apple supports OAuth2 in iOS, so I would expect it in OSX, so look for OAuth2 authentication in the acount settings.
Mozilla Thunderbird runs on OSX and supports Oauth2. Some users have reported that the Mac version of Outlook also works.
Another alternative is to set up 2-step verification in your Google account and use an App Password for Apple Mail.
Last edited 3/27/19
https://support.google.com/mail/thread/3112569?hl=en
Add or remove trusted computers
If you don’t want to enter a 2-Step Verification code or use your Security Key every time you sign in to your Google Account, you can mark your computer or mobile device as trusted. With trusted computers and devices, you don’t need to enter a verification code each time you sign in.
https://support.google.com/accounts/answer/2544838?co=GENIE.Platform%3DDesktop&hl=en