[jiveturkey]

> TL;DR: Don't overthink it, just send a verification email.

pretty bad advice, if taken only as written, without adding more flavor on top.

the major email providers will penalize you if you generate too many undeliverable emails. thus, if you just send a verification email without any pre-validation, it's pretty easy to get into a DoS situation where current/valid users don't get important email sent to them, or that email is significantly delayed, plus incur huge operating cost to resolve the problem.

some form of rate limiting is needed, plus IMHO it's better to use a verifier service or your own heuristic or ML model to test for email validity including valid but fake/spammy/disposable addresses.

sorry, but we are way past the point of being able to have nice things, esp. when we're talking about email.

the "lies" part of the content is great. people do assume all those wrong things. however the TLDR is just wrong, and potentially harmful.

[trumpdong]

I think the only way to deal with that right now is to hire a company whose job is to deal with it. They'll random-check your outgoing emails are indeed what you say they are, and they maintain a reputation with the big providers for checking it properly.

What pre-validation could you do that would possibly be useful?

[jiveturkey]

entropy check, for one

[teo_zero]

> the major email providers will penalize you if you generate too many undeliverable emails.

I suspect the rate at which new users may try to create new accounts and type a wrong email address is too low to be noticed by reputation metrics.

[AndroTux]

there's bad actors that use bots to sign up to websites using bogus data.

[teo_zero]

Wait! Are you saying that you process new registration attempts without any rate limit, captcha, etc? Because the moment to filter out (or limit) bad actors is before they submit an email address, not through it.

[AndroTux]

Yeah, good luck with that. Captchas are basically useless in today’s world, so are IP rate limits for anything just a little sophisticated. Of course it helps, but if you think this solves all problems, you live in a dream world.