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Email Regex that works 99.99%

emailregex.com

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Re: Email Regex that works 99.99%

#61

Post by tom-lord »

gdrulia wrote: post #43
lucaspiller wrote: post #12

Earlier quoted context omitted.

Not sure why this has been downvoted, but yes these sort of things do cause more problems than they solve. Case in point, at work the other day I found a bug in a service I manage. It consists of a front end form (built by one team), which submits data to another system (built by my team), which then passes the data to a third party. The third party was rejecting the data we were trying to send them as the email addr…

So what caused the problem, wasn't that front end and 3rd party was checking if email is valid, but the fact that there is no standard way of checking it. I'm not saying that checking email address with regex is good way of doing it, but there is countless examples of people doing it and it would help a lot if everyone would use one standardized regex for that.

As others have suggested, the best "standardised regex" solution would just be something like:

    /.*@.*/
Some people aren't happy with this because it allows invalid emails to be entered. But the alternative - such as what's being attempted here - is a nightmare!

Even if there was a standardised regex for all emails, which would not break when new TLDs are released, or new unicode characters are supported, or whatever, there would still be no guarantee that someemailaddress@domain.com is actually valid!

Your best bet is to simply allow users to enter anything (with perhaps some minor regex check like I did above), perhaps ask them to enter it twice, and perhaps send an account validation email.

Re: Email Regex that works 99.99%

#62

Post by Piskvorrr »

PeterWhittaker wrote: post #50
Piskvorrr wrote: post #19

Earlier quoted context omitted.

The assumption here is "0. create a regex that does not have false negatives". You seem to be taking the author's word for the "99.9% Works" part - based on what? (Exactly.)

Correctness and utility are two different things, feel free to investigate the former whilst we discuss the latter....

Well thank you, I doubt I would have come to such conclusion by myself. Are you saying that "turn away 0.1% of your customers" is a useful approach? Well, your call, I guess.

Re: Email Regex that works 99.99%

#64

Post by comboy »

pikzen wrote: post #11

Alternatively, don't validate email addresses with a regex because it's pointless. Check that at least an '@' symbol is present and just send a damn email already[0]. Or better, don't send a damn email at all and let them access it because it's pointless to have an extra verification step. If you really want to do some clientside validation, just keep a basic regex and warn the user if the address doesn't seem right.…

Regexps are not only about validation. E.g. sometimes you want to scan some text for e-mails (to highlight them, protect, scrap or whatever).

Although for most languages if there's nothing built in, there's at least one lib that provides it. I prefer using that over copy-pasting it from some random website.

Re: Email Regex that works 99.99%

#65

Post by PeterWhittaker »

Piskvorrr wrote: post #62
PeterWhittaker wrote: post #50

Earlier quoted context omitted.

Correctness and utility are two different things, feel free to investigate the former whilst we discuss the latter....

Well thank you, I doubt I would have come to such conclusion by myself. Are you saying that "turn away 0.1% of your customers" is a useful approach? Well, your call, I guess.

Whoa, there: You're shifting your argument. Are you now accepting that it is 99+% correct? Your original objection was as to the correctness of the regex.

If it is 80% good, then, yeah, your underlying assertion is likely good: Too little coverage to be all that useful. But 99+% coverage? For a quick pass filter? That's pretty good, we can work with those numbers.

After all, one could have multiple layers of progressively more accurate but progressively slower filters. Not an uncommon or unusual approach.

Besides, the JS version could be very useful as a quick pass usability check, validating whether the user made a silly mistake. And adding some logic to record the bogus entry, compare it to what they write next, pass it to the server if need be, can all be very useful.

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