How to match a specific email with RegEx

Question

I want to extend the standard asp.net email regex validator to exclude a specific email.

This is the original:

 ValidationExpression="(\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*)"

This is the extended that I produced:

 ValidationExpression="(\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*)|(?!^email\@email\.com$)"

Can't figure out why this doesn't work

P.s. I know that the standard asp.net regex validator is not recommended for email validation, but it is OK for me.

I don't know ASP, but your snippet seems to miss a closing `)` at the end before the `"` — Gilles Quénot, May 13 '12 at 21:11
I don't know ASP, but regex is not a tool for matching **specific** strings. Can't you create a black list of some sort? P.S. Isn't that an OR between the initial pattern and the address? — Lev Levitsky, May 13 '12 at 21:14

score 1 · Answer 1 · edited May 23 '17 at 12:11

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It does not work as the first part of your pattern matches so it doesn't use your negated second part. You are basically checking if pattern1 or pattern2 matches.

Have a look at https://stackoverflow.com/a/271946/832273 how to create your own validator. This allows you to do all kind of different checks in your program yourself without the need to put everything into your regex.

edited May 23 '17 at 12:11

Community

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answered May 13 '12 at 21:14

Ulrich Dangel

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score 1 · Accepted Answer · edited May 14 '12 at 10:28

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^(?!^email@email\.com$)[originalregexhere]

This is doing a negative lookahead right at the beginning of the matching.

The full example:

ValidationExpression="(?!^email@email\.com$)(\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*)"

edited May 14 '12 at 10:28

Registered User

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answered May 13 '12 at 21:19

usr

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How to match a specific email with RegEx

2 Answers2