Comment by amichal

Edit: https://www.twilio.com/en-us/blog/insights/leveraging-gmail-...

Shows you how to use googles thing if you are a sender to know if @gmail folks are reporting you. It doesnt address what to do if someone's @gmail is doing this to you (a workspace custom domain yes)... @gmail are rate-limited to a few 1000s per day per gmail address but this is still a lot obviously