Regular expression: validate email

I found this regualr expression to validate email but it accepts emails like this:

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

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123@4.3

Microsof's site has that : http://msdn.microsoft.com/en-us/library/aa479013.aspx
but 123@4.3 is not a valid email addess....


I need valid email addresses like test_testing@test.com or .gov, etc


Tried these 2 as well but they didnt accept examples like this :something@test.com.

"^[a-zA-Z][\w\.-]*[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$"

--and this one

b[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b

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LVL 8
CamilliaAsked:
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WebF00LCommented:
Hi,


Give
\b[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b

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A try

http://www.regular-expressions.info/regexbuddy/email.html

//WebFooL Untangle Evangelist
BuggyCoderCommented:
try this:-

^((?>[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+\x20*|"((?=[\x01-\x7f])[^"\\]|\\[\x01-\x7f])*"\x20*)*(?<angle><))?((?!\.)(?>\.?[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+)+|"((?=[\x01-\x7f])[^"\\]|\\[\x01-\x7f])*")@(((?!-)[a-zA-Z\d\-]+(?<!-)\.)+[a-zA-Z]{2,}|\[(((?(?<!\[)\.)(25[0-5]|2[0-4]\d|[01]?\d?\d)){4}|[a-zA-Z\d\-]*[a-zA-Z\d]:((?=[\x01-\x7f])[^\\\[\]]|\\[\x01-\x7f])+)\])(?(angle)>)$

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http://regexlib.com/DisplayPatterns.aspx?AspxAutoDetectCookieSupport=1
http://www.codeproject.com/Articles/22777/Email-Address-Validation-Using-Regular-Expression
CamilliaAuthor Commented:
This one, as I posted, doesnt work. For example, I try test@i.com. It gets rejected by this

\b[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b

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The one posted by BuggyCoder doesnt work. I plug it in ASP.Net aspx page and there are characters that throw errors.

Should I be using the one Microsoft is using?
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BuggyCoderCommented:
well well well, if you are using it in aspx page then do something like this:-

 public const string MatchEmailPattern =
                  @"^(([\w-]+\.)+[\w-]+|([a-zA-Z]{1}|[\w-]{2,}))@"
     + @"((([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\.([0-1]?
                        [0-9]{1,2}|25[0-5]|2[0-4][0-9])\."
     + @"([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\.([0-1]?
                        [0-9]{1,2}|25[0-5]|2[0-4][0-9])){1}|"
     + @"([a-zA-Z]+[\w-]+\.)+[a-zA-Z]{2,4})$";

just add @ before string, i hope you are using c#.
Try visiting this link:-
http://www.codeproject.com/Articles/22777/Email-Address-Validation-Using-Regular-Expression
CamilliaAuthor Commented:
i am using C# but what you have throws errors. This is what i have now:

<asp:RegularExpressionValidator  ID="RegularExpressionValidator1" runat="server"  
                                      
                                     Text="Invalid email address!"
                                    ErrorMessage="Invalid email address!" 
                                    ControlToValidate="txtEmail"     
                                    ValidationExpression="\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"/>

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Yes, i saw that link as well. But there has a be a better way of doing this. How's the performance of using such a long regualr expression??
BuggyCoderCommented:
this is the one i found on MSDN:-

^(?("")("".+?""@)|(([0-9a-zA-Z]((\.(?!\.))|[-!#\$%&'\*\+/=\?\^`\{\}\|~\w])*)(?<=[0-9a-zA-Z])@))(?(\[)(\[(\d{1,3}\.){3}\d{1,3}\])|(([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,6}))$

try to add escape characters when you wrap it in a string variable on in control parameter........ or simply replace  " with '(single quote)
CamilliaAuthor Commented:
I changed double quotes to single but get syntax error. Not sure what you mean by escape characters...


 ValidationExpression="^(?('')(''.+?''@)|(([0-9a-zA-Z]((\.(?!\.))|[-!#\$%&'\*\+/=\?\^`\{\}\|~\w])*)(?<=[0-9a-zA-Z])@))(?(\[)(\[(\d{1,3}\.){3}\d{1,3}\])|(([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,6}))$"/>

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Terry WoodsIT GuruCommented:
You might find this article interesting: http://www.regular-expressions.info/email.html

It's the same site as WebF00L's link, but with explanations.
BuggyCoderCommented:
here have a look at what are escape sequences or characters:-
http://msdn.microsoft.com/en-us/library/ms228362.aspx
CamilliaAuthor Commented:
you think i should use that one? test@i.com is not valid probably because of "i.com"....that probably below doesnt allow:

\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b

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Or should I stick with what MS has but it allows stuff like 123@4.3

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

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Terry WoodsIT GuruCommented:
Maybe you should ask yourself what are the consequences of an invalid email address? If you have users setting up an account of some sort, it's a common technique to send an email to them to validate it's really them. Otherwise even a valid email address may not have the desired person at the other end.
CamilliaAuthor Commented:
Terry, you think i should stick with what MS has in their site?
ValidationExpression="\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"/>

We won't use the email to send validation emails. It's just to have the user's email address. I think it would be ok to keep the same regualr expression that MS has, correct?
Terry WoodsIT GuruCommented:
Unless the ^ and $ are already applied automatically, you'd probably want:

ValidationExpression="^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$"/>

Whether or not it works for you will depend on the consequences of a valid email address being rejected. I've seen users with a surname like O'Leary who use the apostrophe in their email address - technically it's valid, but your pattern doesn't allow it. Personally, I'd tend towards being too lenient rather than too strict.

If you wanted to relax your pattern, you could use something like:
ValidationExpression="^[^\s+.@-]+([-+.][^\s+.@-]+)*@[^\s+.@-]+([-.][^\s+.@-]+)*\.[^\s+.@-]+([-.][^\s+.@-]+)*$"/>

I've replaced all the occurrences of \w with [^\s+.@-]

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CamilliaAuthor Commented:
let me try that.
CamilliaAuthor Commented:
The latest one accepts 123@4.5  and I'm assuming it's ok because I want it to be flexible. Correct?
Terry WoodsIT GuruCommented:
Yes.
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