Email forced popup

katepecora wrote:

Any idea if there is a way to turn off this setting?

There is no setting to turn off, but you can remove your Google Mail account from Mail and use Google's webmail client instead—which is probably what Google wants you to do, so they can inundate you with even more advertisements.

Better yet, uninstall Google from your Mac. Installing Google infests a Mac in the same manner as a "computer virus", if such a thing exists on a Mac, which it doesn't. Google does that so that it can continually harvest your personal information and sell it. I don't let Google anywhere near any of my Macs.

Since its inception Apple has bent over backwards in an effort to make Google's highly nonstandard email service work with their Mail client. Perhaps Apple will block Google from their recent behavior, or not. Perhaps Google will again seek to circumvent it, or not. Regardless of that outcome, Google's pursuit of your personal information will continue at your expense. Whether you want to tolerate that is for you to decide.

Are you using Google for your email service provider, or did you install some other Google product or service?

A number of similar posts conclude that if you installed Google, that's the way Google wants your Mac to work:

Issues with mail app constantly automatic… - Apple Community

Those reports are identical to yours: Mail opens every thirty minutes or so.