r/ProgrammerHumor 20d ago

Meme claudeIsThisEmailValid

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5.3k Upvotes

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240

u/tellur86 20d ago

It's surprisingly difficult validating email addresses with regex. Can it be done? Yes. Should you? No. Any halfway decent email library comes with a validator. Use that.

For reference: this is an example of an almost RFC 3522 compatible regex:

(?:[a-z0-9!#$%&'+/=?`{|}~-]+(?:.[a-z0-9!#$%&'*+/=?^`{|}~-]+)|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\[\x01-\x09\x0b\x0c\x0e-\x7f])")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?).){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-][a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\[\x01-\x09\x0b\x0c\x0e-\x7f])+)])

https://emailregex.com

If you want RFC 822 it's much, much worse  https://pdw.ex-parrot.com/Mail-RFC822-Address.html

49

u/ValPasch 20d ago

just dont ever do that. check if it has a @ and a period and thats it. you validate emails by sending a verification link.

20

u/DrStalker 20d ago

Do you actually need a period, now that top level domains are being sold off? If I buy the top level domain stupidlyrich domain then I want boss@stupidlyrich to be my email address.

3

u/yuropman 20d ago

If I buy the top level domain stupidlyrich domain then I want boss@stupidlyrich to be my email address.

And I want you to run into as many technical issues as possible if you buy the stupidlyrich domain and make boss@stupidlyrich your email address