There are reasons to not block these emails and there are good reasons to block them (but you better not admit that on HN if you do). Number 1 reason to reject is: these users never (99.99%) become customers.

That said: http://cleanli.st

An API (beta) to validate email addresses. It knows and dynamically detects thousands of dispoable email domains (including all mailinator domains).

Of course there are some that do! But admitting that here isn't appreciated:

https://news.ycombinator.com/item?id=4969545