C#-Regular expression for email, but exclude "hotmail,gmail,yahoo"

Question

How can I rewrite this regular expression in order to match all email addresses, but not those
which contains "hotmail,gmail and yahoo". So far I wrote this:

^([a-zA-Z0-9_\-\.]+)@(?<!hotmail|gmail|yahoo)((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$

More localized version: _"C#-Regular expression for email, but exclude “[email protected]”"_ — gdoron, Mar 25 '13 at 09:42
**Don't use regular expressions to validate e-mail addresses!** http://stackoverflow.com/questions/201323/using-a-regular-expression-to-validate-an-email-address — Carsten, Mar 25 '13 at 09:43

MikeM · Accepted Answer · 2013-03-25T10:05:13.940

5

Change the negative lookbehind to a negative lookahead by removing the <, and reposition it as follows

^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(?!hotmail|gmail|yahoo)(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$

The above assumes that "hotmail,gmail and yahoo" would directly follow the @.

Shorter equivalent:

@"^([\w.-]+)@(\[(\d{1,3}\.){3}|(?!hotmail|gmail|yahoo)(([a-zA-Z\d-]+\.)+))([a-zA-Z]{2,4}|\d{1,3})(\]?)$"

edited Mar 25 '13 at 10:05

answered Mar 25 '13 at 09:57

MikeM

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Hello, I tried your solution but this email does not match the RegEx : [email protected]. It should match because it's "gmaill" and not "gmail" – Aymen Jul 17 '20 at 09:05

C#-Regular expression for email, but exclude "hotmail,gmail,yahoo"

1 Answers1