To use a Gmail account to send you CCTV equipment’s email notifications, you now need to set up a unique third-party app password for it. Most other email providers still allow third-party apps or devices to use your account with your normal password for it, but Google no longer permits this as...
As of the 30th May 2022, Google has removed the support for use of third-party apps or devices which can use your Gmail address using only your normal username and password.
Google's statement about it is here:
https://support.google.com/accounts/answer/6010255?hl=en
As CCTV equipment is a...