So a client contacted me today and said when he attempts to migrate from gmail, the test connection button fails, once he's authorized everything.
I tested myself, and sure enough the same thing happened to me. I received an email in my gmail inbox from google stating the following:
Google just blocked someone from signing into your Google Account [redacted]@gmail.com from an app that may put your account at risk.
Less secure app
Friday, July 28, 2017 5:28 PM (GMT)
Don't recognize this activity?
If you didn't recently receive an error while trying to access a Google service, like Gmail, from a non-Google application, someone may have your password.
SECURE YOUR ACCOUNT
Are you the one who tried signing in?
Google will continue to block sign-in attempts from the app you're using because it has known security problems or is out of date. You can continue to use this app by allowing access to less secure apps, but this may leave your account vulnerable.
I know there is an update to version 15, but the release notes don't mention anything about gmail or migration.
Any thoughts on what is causing this?