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Dear devs: Plus signs are valid
9 points by 0xbadcafebee on Nov 23, 2021 | hide | past | favorite | 9 comments
I have been trying to use a '+' sign in my e-mails to separate accounts into aliased folders for a few months now, and about half of all services that accept an e-mail address think that the plus sign is an illegal character. It's not!

If you implement an e-mail validator, please follow the RFCs and don't just throw together a regex that you think looks good. Here are some pages explaining the RFCs:

- https://jkorpela.fi/rfc/822addr.html

- https://www.mailboxvalidator.com/resources/articles/acceptable-email-address-syntax-rfc/



You're right and still it's pure stubbornness on your part. A waste of energy.

The world won't change because you say so. Just use a dash to separate your constituent parts instead of a plus sign, and you won't have that problem ever again.

(I know someone who has been complaining about exactly this for more than twenty years now. Surprisingly it never seems to get old for him. Some people just need a "standard complaint".)


Plus has different behavior on Google mail, is why.

Foo+anything@ goes to foo@. This is an easy way to track who's selling your email.

Not every complaint you don't understand is invalid


Maybe that IS the reason some services treat it as an illegal character. They know how Gmail works and want to prevent you from figuring out what they do with your email.


What is even worse some have hardcoded regexes, so if your domain does not end with .com it does not accept it as a valid email...

That + behavior is pretty standard and not related to google only.


+ allows you to have infinite accounts on the same email. It might be disabled on purpose.


We remove the plus sign and everything after it. Spammers love the + alias.


Homoglyph: https://en.wikipedia.org/wiki/Homoglyph

UniCode 'Confusables' Visual-Spoofing: https://unicode.org/reports/tr36/#visual_spoofing

The Invisible JavaScript Backdoor: https://certitude.consulting/blog/en/invisible-backdoor/

<quote> There are many other characters that look similar to the ones used in code which may be used for such proposes, (e.g. “／”, “−”, “＋”, “⩵”, “”, “⫽”, “꓿”, “∗”). Unicode calls these characters “confusables”. </quote>


Spaces are allowed in filenames, but I'm still not going to use them.


Yeah, got to be some regex that is everyone is using that's wrong




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