[nullindividual]

Developers and regex on email is always a terrible idea. So many fail to understand what the RFC allows (virtually anything). Can't tell you how often websites will reject an email address with a two-character localpart :-(

[edricj]

For such cases (refer to @icloud.com), no idea if we should take it so seriously…

For now, our goal is to detect disposable mails from online free providers.

[KomoD]

Yeah I can relate to that... some don't even realize TLDs longer than 3 chars exist (my primary domain uses a 4 char TLD)