By the way, please don’t write regex to try to validate email addresses. Seriously.
Amen.
There are libraries for that; some of them are even good.
Spoiler alert: Few of them are good, and those few are so simple that you might as well not use a library.
The only way to correctly validate an email address is to send a message to it, and verify that it arrived.
You can use a regex to do basic validation. That regex is .+. Anything beyond that is a waste of time.
There are also cases where you want to have a disallow list of known bad email providers. That’s also part of the parsing and validating.
It’s a valid need, but a domain blacklist isn’t part of email parsing and if you conflate the two inside your program then you’re mixing concerns.
Why is the domain blacklist even in your program? It should be a user configurable file or a list of domains in the database.
Which ones? In RFC 5322 every address contains an addr-spec at some point, which in turn must include an @. RFC 6854 does not seem to change this. Or did I misread something?
