Regular Expression for Email Address validation in C#

By Ankit Goyal | June 6, 2009 | 10,313 views
Category .NET

About author Working on .NET technologies for past 2yrs. I am very passionate about the new features which get introduced in the technology. I am here to share the new features i get to know in the world of Microsoft. Follow me on twitter @ankygoyal Read more from this author

The task at hand is to validate the Textbox in asp.net for a valid email address.

We can attach a RegularExpressionValidator to the text box with the following regular expression:

<asp:RegularExpressionValidator ValidationExpression="^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$" ID="rxpEmail" runat="server"
ErrorMessage="Email Address is not valid" Text="*" Display="Static" ControlToValidate="txtEmail"></asp:RegularExpressionValidator>

UPDATES
Well i searched the net for the standards of a valid email id and i came across with a wonderful article at

I Knew How To Validate An Email Address Until I Read The RFC

It gives a an idea of what an exact RFC standard for the email id is.

I believe that we should follow validations which are quite obvious to the users and allow only standard email addresses.

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12 comments | Add One

Comments

JL - 06/6/2009 at 8:41 am
I don’t understand the right part of the regex.
It would match:
name1.name2@mail.123

I don’t think tld can be numbers.
Ankit Goyal - 06/7/2009 at 10:07 am
i think we can have email ids of type
abc@cmpnyname.local1
David - 06/7/2009 at 11:34 pm
“+” is also valid character.

e.g.

yourname+thispartgetsignored@gmail.com

is equivalent to:

yourname@gmail.com
Ankit Goyal - 06/8/2009 at 12:29 am
new info for me….
have never tried this…i will work on it…
thnkss david…
Micah Burnett - 06/8/2009 at 7:33 am
I prefer a dumbed down the expression that catches most of the real-world problems instead of verifying every possible combination. The ultimate validation is when the mail server rejects the address…then you know for sure!

Our Republic
Ankit Goyal - 06/8/2009 at 7:40 am
Micah u r rite as the ultimate validation for a email address is achieved when we ping the mail server for the specified email address…
john - 10/29/2009 at 12:37 pm
Hi, I could see one nice method here http://www.Tctcworld.com. if u need go through it..
Craig - 11/6/2009 at 9:56 am
If you want to validate e-mail addresses by pinging their mail server just use EmailVerify.NET, a .NET component which can test e-mail syntactically, verify the DNS MX records for the each domain and connect to each mail server to check if the mailbox exists or not.

It works like a charm!!
There’s also a nice demo on their website: http://www.emailverify.net

Hope this helps.
Margish - 02/19/2010 at 8:00 am
This worked for my task
[a-z]*\.*[a-z]*@[a-z]*\.[a-z]*