正则表达式电子邮件模式:

^(?:[\\w\\!\\#\\$\\%\\&\\'\\*\\+\\-\\/\\=\\?\\^\\`\\{\\|\\}\\~]+\\.)*[\\w\\!\\#\\$\\%\\&\\'\\*\\+\\-\\/\\=\\?\\^\\`\\{\\|\\}\\~]+@(?:(?:(?:[a-zA-Z0-9](?:[a-zA-Z0-9\\-](?!\\.)){0,61}[a-zA-Z0-9]?\\.)+[a-zA-Z0-9](?:[a-zA-Z0-9\\-](?!$)){0,61}[a-zA-Z0-9]?)|(?:\\[(?:(?:[01]?\\d{1,2}|2[0-4]\\d|25[0-5])\\.){3}(?:[01]?\\d{1,2}|2[0-4]\\d|25[0-5])\\]))$

以下代码是基于微软在github上的数据注释实现的，我认为这是对电子邮件最完整的验证:

public static Regex EmailValidation()
{
    const string pattern = @"^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\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);
}

我在MSDN上找到了一个很好的文档。

如何:验证字符串是否在有效的电子邮件格式 http://msdn.microsoft.com/en-us/library/01escwtf.aspx (请注意，这段代码还支持在Internet域名中使用非ascii字符。)

有两个实现，用于。net 2.0/3.0和用于。net 3.5及更高版本。 2.0/3.0版本为:

bool IsValidEmail(string strIn)
{
    // Return true if strIn is in valid e-mail format.
    return Regex.IsMatch(strIn, @"^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$"); 
}

我对这个方法的测试给出:

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

这并不满足rfc 5321和5322的所有要求，但它适用于以下定义。

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

下面是代码

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[] {
        "ma@hostname.com",
        "ma@hostname.comcom",
        "MA@hostname.coMCom",
        "m.a@hostname.co",
        "m_a1a@hostname.com",
        "ma-a@hostname.com",
        "ma-a@hostname.com.edu",
        "ma-a.aa@hostname.com.edu",
        "ma.h.saraf.onemore@hostname.com.edu",
        "ma12@hostname.com",
        "12@hostname.com",
};
var invalidEmails = new[] {
        "Abc.example.com",     // No `@`
        "A@b@c@example.com",   // multiple `@`
        "ma...ma@jjf.co",      // continuous multiple dots in name
        "ma@jjf.c",            // only 1 char in extension
        "ma@jjf..com",         // continuous multiple dots in domain
        "ma@@jjf.com",         // continuous multiple `@`
        "@majjf.com",          // nothing before `@`
        "ma.@jjf.com",         // nothing after `.`
        "ma_@jjf.com",         // 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));
}

这段代码将有助于在c#.Net中使用正则表达式验证电子邮件id。它很容易使用

if (!System.Text.RegularExpressions.Regex.IsMatch("<Email String Here>", @"^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$"))
        {
            MessageBox.show("Incorrect Email Id.");
        }

目前对我来说，最好的方法是使用FluentValidation库。它有一个内置的电子邮件地址验证器。用法非常简单，你不必考虑正则表达式。

using FluentValidation;
public class TestClass
{
   public string Email { get; set; }
}

public class TestClassValidator: AbstractValidator<TestClass>
{
   public TestClassValidator()
   {            
      RuleFor(x => x.Email).EmailAddress().WithMessage($"nameof{(TestClass.Email)} is not a valid email address");
   }
}

我知道这个问题很久以前就被问过了，但也许用一种新的方法来刷新答案会对某人有所帮助。