Comments on: TIP: Simple Regular Expression for Email Validation

By: Ian

Ian — Tue, 01 Dec 2009 21:50:55 +0000

I wrote a script that compared various regexs from around the web against a set of sample data and the best one I found was:

/^[-_a-z0-9\'+*$^&%=~!?{}]++(?:\.[-_a-z0-9\'+*$^&%=~!?{}]+)*+@(?:(?![-.])[-a-z0-9.]+(?

More details @ Comparing E-mail Address Validating Regular Expressions

By: CakePHP – Email Validation « Eureka!

CakePHP – Email Validation « Eureka! — Fri, 18 Sep 2009 01:32:11 +0000

[...] Reference: TIP: Simple Regular Expression for Email Validation [...]

By: Bernie

Bernie — Tue, 18 Aug 2009 15:23:21 +0000

E-mail validation means RFC 5322. If your regex doesn’t match it you are perceived as thus redefining this standard; how angry would you be if you have a valid e-mail address according to the real standard and someone else’s web page tells them they don’t according to their regex?

Here’s what to do.

1. Check there’s a valid MX record for the domain.
2. Do an SMTP call-forward to that domain: connect to the lowest priority MX on port 25 and issue
EHLO my.machine.name[crlf]
MAIL FROM:[crlf]
RCPT TO:[crlf]
RSET
QUIT

Wait for a banner first, and a response each time beginning “2nn “.

After the RCPT TO, “2nn ” means e-mail address deliverable, “4nn ” means not currently deliverable, “5nn ” means not deliverable. Up to you how you treat “4nn “.

If the above is too difficult, just send them an e-mail containing a token needed to complete whatever your process is. Then not only do you know it’s a valid address, but even that it is the user’s actual address.

By: Kulbir Saini

Kulbir Saini — Tue, 18 Aug 2009 09:31:14 +0000

@Edward, Tushar Thanks for sharing your regex(s). I’ll test them out.
@Bernie Take it easy dude. I am not defining a standard. I needed a simple regex for email validation in my app and I wrote it. Period.

By: Tushar(Chia)

Tushar(Chia) — Tue, 18 Aug 2009 02:15:07 +0000

Here is the Jquery Email verification function function isValidEmailAddress(emailAddress) { var pattern = new RegExp(/^(("[\w-\s]+")|([\w-]+(?:\.[\w-]+)*)|("[\w-\s]+")([\w-]+(?:\.[\w-]+)*))(@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$)|(@\[?((25[0-5]\.|2[0-4][0-9]\.|1[0-9]{2}\.|[0-9]{1,2}\.))((25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\.){2}(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\]?$)/i); return pattern.test(emailAddress); } Regards

By: Bernie

Bernie — Mon, 17 Aug 2009 21:28:20 +0000

Your regex does not appear to be based on RFC 5322.

What was your source? It looks to me like you’re choosing to reinvent a standard which has carefully been considered by more appropriate people.

This is exactly the sort of thing the F/OSS community accuses proprietary software houses of doing.

By: Edward Rudd

Edward Rudd — Mon, 17 Aug 2009 21:20:26 +0000

Here is my validation Regex which matches a bit more that yours. Specifically emails with apostrophes, which I would prefer not be allowed, but several corporations allow them. also it only allowed a-z in the domain name.

This regex is designed to run in “case-insensitive mode”

this link was a very nice source of why certain characters that are allowed in the email spec probably shouldn’t and aren’t by most systems.

http://www.remote.org/jochen/mail/info/chars.html

^(?:(?:[\-+%=_'a-z0-9]+)(?:\.(?![\.@]))?)+@(?:[a-z0-9\-]+\.)+[a-z]+

Though personally I like the regex on this page

http://ex-parrot.com/~pdw/Mail-RFC822-Address.html

That’s a good one to scare anyone.

By: Bernie

Bernie — Mon, 17 Aug 2009 21:19:43 +0000

http://en.wikipedia.org/wiki/E-mail_address#RFC_specification