@cratermoon, out of interest what is the biggest negative impact you have seen from this?

I have seen a lot of people suggest blocking all free email domains or only supporting a small subset of whitelisted domains, I expect businesses to see pretty quickly that they lose a decent percent of legitimate signups.

The legitimate signups being the good measure as if you are filtering out disposable emails for instance you will lower your overall signups but should have no negative impact on revenue (potentially positive as people who would signup with disposable accounts now signup with accounts you can contact them on and they are happy to convert to paying with).

We try to make this easy be doing email validation for free at any scale and only flagging the people we are sure are not valid (disposable, unreachable domains etc.)