• ono@lemmy.ca
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    6 months ago

    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.

    • Jesus_666@feddit.de
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      6 months ago

      You can use a regex to do basic validation. That regex is .+@.+. Anything beyond that is a waste of time.

        • Jesus_666@feddit.de
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          6 months ago

          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?

            • Jesus_666@feddit.de
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              6 months ago

              And it’s matched by .+@.+ as it contains an @.

              Remember, we’re taking about regular expressions here so .+ means “a sequence of one or more arbitrary characters”. It does not imply that an actual dot is present.

              (And I overlooked the edit. Oops.)

      • hansl@lemmy.world
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        6 months ago

        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.

        • Tramort@programming.dev
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          6 months ago

          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.

        • anti-idpol action@programming.dev
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          6 months ago

          fuck any website that requires an account to just READ it’s stupid content and at the same time blocks guerrillamail/10minutemail (looking at you, Glassdoor,I don’t want to get fucking spam just so that I can check approximate salary in a company)

        • ono@lemmy.ca
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          6 months ago

          disallow list of known bad email providers.

          Imagine giving someone your phone number, and having them say you have to get a different one because they don’t like some of the digits in it.

          I have seen this nonsense more times than I care to remember. Please don’t build systems this way.

          If you’re trying to do bot detection or the like, use a different approach. Blacklisting email addresses based on domain or any other pattern does a poor job of it and creates an awful user experience.

          (And if it prevents people from using spam-fighting tools like forwarding services, then it’s directly user-hostile, and makes the world a worse place.)