How do email search services work on the site?

Question

Python

For example, here is the result with hunter(dot)io:

The result was too fast, it looks like they already had emails in the database (quite possibly). But still, how is the initial collection? They don’t parse stupidly all the pages that they can find in search of the email tag, there can be hundreds of thousands of pages, as is the case with habr.

Answer 1

parsing + bases + heuristics
, no one guarantees delivery to you))