Regex Email validation

Question

I use this        w   -       w -         w  2 3         regexp to validate the email     w   -    - this is for the first-level domain  many letters and numbers  also point and hyphen     w -    - this is for second-level domain       w  2 3     - and this is for other level domains from 3 to infinity  which includes a point and 2 or 3 literals  what s wrong with this regex   EDIT it doesn t match the  something someth ing  email

User · Answer

This does not meet all of the requirements of RFCs 5321 and 5322, but it works with the following definitions.

@"^([0-9a-zA-Z]([\+\-_\.][0-9a-zA-Z]+)*)+"@(([0-9a-zA-Z][-\w]*[0-9a-zA-Z]*\.)+[a-zA-Z0-9]{2,17})$";

Below is the code

const String pattern =
   @"^([0-9a-zA-Z]" + //Start with a digit or alphabetical
   @"([\+\-_\.][0-9a-zA-Z]+)*" + // No continuous or ending +-_. chars in email
   @")+" +
   @"@(([0-9a-zA-Z][-\w]*[0-9a-zA-Z]*\.)+[a-zA-Z0-9]{2,17})$";

var validEmails = new[] {
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
};
var invalidEmails = new[] {
        "Abc.example.com",     // No `@`
        "A@b@[email protected]",   // multiple `@`
        "[email protected]",      // continuous multiple dots in name
        "[email protected]",            // only 1 char in extension
        "[email protected]",         // continuous multiple dots in domain
        "ma@@jjf.com",         // continuous multiple `@`
        "@majjf.com",          // nothing before `@`
        "[email protected]",         // nothing after `.`
        "[email protected]",         // nothing after `_`
        "ma_@jjf",             // no domain extension 
        "ma_@jjf.",            // nothing after `_` and .
        "ma@jjf.",             // nothing after `.`
    };

foreach (var str in validEmails)
{
    Console.WriteLine("{0} - {1} ", str, Regex.IsMatch(str, pattern));
}
foreach (var str in invalidEmails)
{
    Console.WriteLine("{0} - {1} ", str, Regex.IsMatch(str, pattern));
}

User · Answer

This one prevents invalid emails mentioned by others in the comments   Abc  example com Abc  123 example com name hotmail toms email  gmail com test -online com   It also prevents emails with double dots   hello  world example  com   Try testing it with as many invalid email addresses as you can find   using System Text RegularExpressions   public static bool IsValidEmail string email        return Regex IsMatch email     A a-z0-9    -    a-z0-9       a-z0-9   - a-z0-9         a-z  2 4  z            amp  amp  Regex IsMatch email          1 64    4 64        6 100             See validate email address using regular expression in C

User · Answer

Try this on for size   public static bool IsValidEmailAddress this string s        var regex   new Regex    a-z0-9     amp              -        a-z0-9     amp              -         a-z0-9     a-z0-9-   a-z0-9        a-z0-9     a-z0-9-   a-z0-9           return regex IsMatch s

User · Answer

I have an expression for checking email addresses that I use   Since none of the above were as short or as accurate as mine  I thought I would post it here        w     amp     -                  w     amp     -                                - w       a-zA-Z  2 4      0-9  1 3     3  0-9  1 3         For more info go read about it here  C      Email Regular Expression  Also  this checks for RFC validity based on email syntax  not for whether the email really exists  The only way to test that an email really exists is to send and email and have the user verify they received the email by clicking a link or entering a token   Then there are throw-away domains  such as Mailinator com  and such  This doesn t do anything to verify whether an email is from a throwaway domain or not

User · Answer

I ve created a FormValidationUtils class to validate email   public static class FormValidationUtils       const string ValidEmailAddressPattern      A-Z0-9    -    A-Z0-9 -      A-Z  2 6          public static bool IsEmailValid string email                var regex   new Regex ValidEmailAddressPattern  RegexOptions IgnoreCase           return regex IsMatch email

User · Answer

I found nice document on MSDN for it   How to  Verify that Strings Are in Valid Email Format http   msdn microsoft com en-us library 01escwtf aspx  check out that this code also supports the use of non-ASCII characters for Internet domain names    There are 2 implementation  for  Net 2 0 3 0 and for  Net 3 5 and higher  the 2 0 3 0 version is   bool IsValidEmail string strIn           Return true if strIn is in valid e-mail format      return Regex IsMatch strIn        w-           0-9  1 3    0-9  1 3    0-9  1 3         w-          a-zA-Z  2 4   0-9  1 3                 My tests over this method give   Invalid   majjf com Invalid  A b c example com Invalid  Abc example com Valid  j  s proseware com Valid  j  server1 proseware com Invalid  js  proseware com Invalid  js proseware  com Valid  ma   ma jjf co Valid  ma  jjf com Invalid  ma  jjf com Invalid  ma jjf  Invalid  ma jjf  com Invalid  ma jjf c Invalid  ma  jjf Invalid  ma  jjf  Valid  ma  jjf com Invalid  ------- Valid  12 hostname com Valid  d j server1 proseware com Valid  david jones proseware com Valid  j s server1 proseware com Invalid  j proseware com9 Valid  j 9  129 126 118 1  Valid  jones ms1 proseware com Invalid  js internal proseware com Invalid  js proseware com9 Invalid  js proseware com9 Valid  m a hostname co Valid  m a1a hostname com Valid  ma h saraf onemore hostname com edu Valid  ma hostname com Invalid  ma hostname comcom Invalid  MA hostname coMCom Valid  ma12 hostname com Valid  ma-a aa hostname com edu Valid  ma-a hostname com Valid  ma-a hostname com edu Valid  ma-a 1hostname com Valid  ma a 1hostname com Valid  ma 1hostname com

User · Answer

1     w     amp     -                  w     amp     -                     - w       a-zA-Z  2 4      0-9  1 3     3  0-9  1 3       2        lt  gt             s            lt  gt             s                           0-9  1 3    0-9  1 3    0-9  1 3    0-9  1 3        a-zA-Z -0-9       a-zA-Z  2

User · Answer

Why not use EF6 attribute based e-mail validation   As you can see above  Regex validation for e-mail always has some hole in it  If you are using EF6 data annotations  you can easily achieve reliable and stronger e-mail validation with EmailAddress data annotation attribute available for that  I had to remove the regex validation I used before for e-mail when I got mobile device specific regex failure on e-mail input field  When the data annotation attribute used for e-mail validation  the issue on mobile was resolved   public class LoginViewModel        EmailAddress ErrorMessage    The email format is not valid        public string Email  get  set

User · Answer

A combination of the above responses  I would use the Microsoft preferred approach of using MailAddress but implement as an extension of string   public static bool IsValidEmailAddress this string emailaddress                try                       MailAddress m   new MailAddress emailaddress               return true                    catch  FormatException                        return false                    Then just validate any string as an email address with   string customerEmailAddress    bert potato com   customerEmailAddress IsValidEmailAddress     Clean simple and portable  Hope it helps someone  Regex for emails are messy   That said MattSwanson has a blog on this very topic and he strongly suggests NOT using regexs and instead just check for     abd maybe a dot  Read his explanation here  https   mdswanson com blog 2013 10 14 how-not-to-validate-email-addresses html

User · Answer

I ve been using the Regex IsMatch     First of all you need to add the next statement   using System Text RegularExpressions    Then the method looks like   private bool EmailValidation string pEmail                     return Regex IsMatch pEmail                                     lt             0-9a-z              -      amp                     w       lt   0-9a-z                                       d 1 3     3  d 1 3        0-9a-z  - w   0-9a-z       a-z0-9   -a-z0-9  0 22  a-z0-9                        RegexOptions IgnoreCase  TimeSpan FromMilliseconds 250        It s a private method because of my logic but you can put the method as static in another Layer such as  Utilities  and call it from where you need

User · Answer

public static bool ValidateEmail string str                                return Regex IsMatch str     w   -     w     w   -   w      w   -   w           I use the above code to validate the email address

User · Answer

Visual studio had this for years    w   -     w     w   -   w      w   -   w      Hope this helps

User · Answer

here is our Regex for this case        a-zA-Z0-9  -           0-9  1 3                                 0-9  1 3    0-9  1 3        a-zA-Z0-9 -                                       a-zA-Z  2 6   0-9  1 3             there are three parts  which are checcked  the last one is propably the one you need  the specific term  2 6  indicates you the min max length of the TLD at the end  HTH

User · Answer

This code will help to validate email id using regex expression in c  Net  it is easy to use  if   System Text RegularExpressions Regex IsMatch   lt Email String Here gt          w   -       w -         w  2 3                               MessageBox show  Incorrect Email Id

User · Answer

string patternEmail        lt email gt  w   w    a-z  0 3     Regex regexEmail   new Regex patternEmail

User · Answer

This is my favorite approach to this so far   public static class CommonExtensions       public static bool IsValidEmail this string thisEmail            gt   string IsNullOrWhiteSpace thisEmail   amp  amp             new Regex       w   -       w -         w  2 3        IsMatch thisEmail       Then use the created string extension like   if   emailAsString IsValidEmail    throw new Exception  Invalid Email

User · Answer

public bool VailidateEntriesForAccount                if    txtMailId Text Trim      string Empty                         if   IsEmail txtMailId Text                                 Logger Debug  Entered invalid Email ID s                    MessageBox Show  Please enter valid Email Id s                     txtMailId Focus                    return false                                    private bool IsEmail string strEmail                Regex validateEmail   new Regex      W      w   -        w  -       A-Za-z   2 4    W    1    W        w   -        w  -       A-Za-z  2 4     W               return validateEmail IsMatch strEmail

User · Answer

STRING SEARCH USING REGEX METHOD IN C   How to validate an Email by Regular Expression   string EmailPattern      w   -     w     w   -   w      w   -   w      if  Regex IsMatch Email  EmailPattern  RegexOptions IgnoreCase         Console WriteLine  Email   0  is valid    Email     else       Console WriteLine  Email   0  is not valid    Email       Use Reference String Regex   Method

User · Answer

There s no perfect regular expression  but this one is pretty strong  I think  based on study of RFC5322  And with C  string interpolation  pretty easy to follow  I think  as well   const string atext     a-zA-Z d      amp      -                  var localPart       atext         atext        var domain       atext         atext        Assert That      gt  EmailRegex   new Regex     localPart   domain     Compiled    Throws Nothing     Vetted with NUnit 2 x

User · Answer

TLD s like  museum aren t matched this way  and there are a few other long TLD s  Also  you can validate email addresses using the MailAddress class as Microsoft explains here in a note      Instead of using a regular expression to validate an email address    you can use the System Net Mail MailAddress class  To determine   whether an email address is valid  pass the email address to the   MailAddress MailAddress String  class constructor    public bool IsValid string emailaddress        try               MailAddress m   new MailAddress emailaddress            return true            catch  FormatException                return false            This saves you a lot af headaches because you don t have to write  or try to understand someone else s  regex

User · Answer

Try the Following Code   using System Text RegularExpressions  if    Regex IsMatch txtEmail Text      a-z A-Z  1 10   -    w     w   w 3              MessageBox Show  Not valid email

User · Answer

This regex works perfectly   bool IsValidEmail string email        return Regex IsMatch email       w     amp     -                  w     amp     -                     - w       a-zA-Z  2 4      0-9  1 3     3  0-9  1 3    z

User · Answer

It has taken many attempts to create an email validator which catches nearly all worldwide requirements for email     Extension method you can call with   myEmailString IsValidEmailAddress      Regex pattern string you can get by calling   var myPattern   Regex EmailPattern    The Code  mostly comments             lt summary gt          Validates the string is an Email Address             lt  summary gt           lt param name  emailAddress  gt  lt  param gt           lt returns gt bool lt  returns gt      public static bool IsValidEmailAddress this string emailAddress                var valid   true          var isnotblank   false           var email   emailAddress Trim            if  email Length  gt  0                           Email Address Cannot start with period                 Name portion must be at least one character                In the Name  valid characters are   a-z 0-9          amp                -                              Cannot have period immediately before   sign                 Cannot have two   symbols                In the domain  valid characters are  a-z 0-9 -                  Domain cannot start with a period or dash                Domain name must be 2 characters   not more than 256 characters                Domain cannot end with a period or dash                 Domain must contain a period             isnotblank   true              valid   Regex IsMatch email  Regex EmailPattern  RegexOptions IgnoreCase   amp  amp                   email StartsWith  -    amp  amp                   email StartsWith       amp  amp                   email EndsWith       amp  amp                    email Contains        amp  amp                   email Contains        amp  amp                   email Contains                           return  valid  amp  amp  isnotblank                   lt summary gt          Validates the string is an Email Address or a delimited string of email addresses             lt  summary gt           lt param name  emailAddress  gt  lt  param gt           lt returns gt bool lt  returns gt      public static bool IsValidEmailAddressDelimitedList this string emailAddress  char delimiter                      var valid   true          var isnotblank   false           string   emails   emailAddress Split delimiter            foreach  string e in emails                        var email   e Trim                if  email Length  gt  0  amp  amp  valid     if valid    false  no reason to continue checking                               isnotblank   true                  if   email IsValidEmailAddress                                          valid   false                                                    return  valid  amp  amp  isnotblank              public class Regex                    lt summary gt              Set of Unicode Characters currently supported in the application for email  etc               lt  summary gt          public static readonly string UnicodeCharacters      -   p L  p M                                                                                         German and French               lt summary gt              Set of Symbol Characters currently supported in the application for email  etc              Needed if a client side validator is being used              Not needed if validation is done server side              The difference is due to subtle differences in Regex engines               lt  summary gt          public static readonly string SymbolCharacters         amp            -                               lt summary gt              Regular Expression string pattern used to match an email address              The following characters will be supported anywhere in the email address                                                                                                 a - z  A - Z  0 - 9                The following symbols will be supported in the first part of the email address before the   symbol                   amp         -                     Emails cannot start or end with periods dashes or                Emails cannot have two   symbols              Emails must have an   symbol followed later by a period              Emails cannot have a period before or after the   symbol               lt  summary gt          public static readonly string EmailPattern   String Format                    w 0  2      1   w 0     -    w 0         w 0     -    w 0                                      0  w    -      0  w       0  w    -    0  w        0  w    -    0  w                    UnicodeCharacters                1                SymbolCharacters

User · Answer

Regex Email Pattern          w               amp            -                                     w               amp            -                                        a-zA-Z0-9     a-zA-Z0-9  -          0 61  a-zA-Z0-9        a-zA-Z0-9     a-zA-Z0-9  -        0 61  a-zA-Z0-9                 01    d 1 2  2 0-4   d 25 0-5       3     01    d 1 2  2 0-4   d 25 0-5

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Best email validation regex    a-z0-9     amp              -        a-z0-9     amp              -         a-z0-9     a-z0-9-   a-z0-9        a-z0-9     a-z0-9-   a-z0-9      And it s usage  -   bool isEmail   Regex IsMatch emailString     A    a-z0-9     amp              -        a-z0-9     amp              -         a-z0-9     a-z0-9-   a-z0-9        a-z0-9     a-z0-9-   a-z0-9     Z   RegexOptions IgnoreCase

User · Answer

To validate your email ID  you can simply create such method and use it        public static bool IsValidEmail string email                var r   new Regex      0-9a-zA-Z   -   w   0-9a-zA-Z      0-9a-zA-Z  - w   0-9a-zA-Z      a-zA-Z  2 9               return  String IsNullOrEmpty email   amp  amp  r IsMatch email           This will return True   False   Valid   Invalid Email Id

User · Answer

Email validation using regex      string pattern      A    a-z0-9     amp              -        a-z0-9     amp              -         a-z0-9     a-z0-9-   a-z0-9        a-z0-9     a-z0-9-   a-z0-9     Z          check first string    if  Regex IsMatch EmailId1   pattern                     if email is valid         Console WriteLine EmailId1    is a valid Email address            Source  email validation c   Validation Without Regex using MailAddress MailAddress String  class constructor  public bool IsEmailValid string emailaddress     try        MailAddress m   new MailAddress emailaddress       return true      catch  FormatException         return false

User · Answer

I think       w   -       w -         w  2 3       should work  You need to write it like  string email   txtemail Text  Regex regex   new Regex       w   -       w -         w  2 3         Match match   regex Match email   if  match Success      Response Write email     is correct    else     Response Write email     is incorrect      Be warned that this will fail if    There is a subdomain after the   symbol  You use a TLD with a length greater than 3  such as  info

User · Answer

The following code is based on Microsoft s Data annotations implementation on github and I think it s the most complete validation for emails   public static Regex EmailValidation         const string pattern          a-z   d        amp       -                  u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF        a-z   d        amp       -                  u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF          x22      x20  x09    x0d x0a     x20  x09        x01- x08 x0b x0c x0e- x1f x7f   x21   x23- x5b    x5d- x7e    u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF         x01- x09 x0b x0c x0d- x7f    u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF          x20  x09    x0d x0a     x20  x09      x22        a-z   d   u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF      a-z   d   u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF    a-z   d -          u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF     a-z   d   u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF           a-z    u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF      a-z    u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF    a-z   d -          u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF     a-z    u00A0- uD7FF uF900- uFDCF uFDF0- uFFEF               const RegexOptions options   RegexOptions Compiled   RegexOptions IgnoreCase   RegexOptions ExplicitCapture          Set explicit regex match timeout  sufficient enough for email parsing        Unless the global REGEX DEFAULT MATCH TIMEOUT is already set     TimeSpan matchTimeout   TimeSpan FromSeconds 2        try               if  AppDomain CurrentDomain GetData  REGEX DEFAULT MATCH TIMEOUT      null                        return new Regex pattern  options  matchTimeout                       catch                  Fallback on error               Legacy fallback  without explicit match timeout      return new Regex pattern  options

User · Answer

I think your caret and dollar sign are part of the problem You should also modify the regex a little  I use the next            w -       w-         w  2 3

User · Answer

Try this  it s working for me   public bool IsValidEmailAddress string s        if  string IsNullOrEmpty s           return false      else               var regex   new Regex    w   -     w     w   -   w      w   -   w               return regex IsMatch s   amp  amp   s EndsWith

User · Answer

new System ComponentModel DataAnnotations EmailAddressAttribute   IsValid input

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Just let me know IF it doesn t work     public static bool isValidEmail this string email         string   mail   email Split new string            StringSplitOptions None        if  mail Length    2          return false         check part before           if  mail 0  Length  lt  1          return false       System Text RegularExpressions Regex regex   new System Text RegularExpressions Regex     a-zA-Z0-9  -             if   regex IsMatch mail 0            return false         check part after           string   domain   mail 1  Split new string            StringSplitOptions None        if  domain Length  lt  2          return false       regex   new System Text RegularExpressions Regex     a-zA-Z0-9  -            foreach  string d in domain                if   regex IsMatch d               return false               get TLD     if  domain domain Length - 1  Length  lt  2          return false       return true

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