一个简单的没有使用Regex(我不喜欢它的可读性差):

bool IsValidEmail(string email)
{
    string emailTrimed = email.Trim();

    if (!string.IsNullOrEmpty(emailTrimed))
    {
        bool hasWhitespace = emailTrimed.Contains(" ");

        int indexOfAtSign = emailTrimed.LastIndexOf('@');

        if (indexOfAtSign > 0 && !hasWhitespace)
        {
            string afterAtSign = emailTrimed.Substring(indexOfAtSign + 1);

            int indexOfDotAfterAtSign = afterAtSign.LastIndexOf('.');

            if (indexOfDotAfterAtSign > 0 && afterAtSign.Substring(indexOfDotAfterAtSign).Length > 1)
                return true;
        }
    }

    return false;
}

例子:

IsValidEmail（“@b.com”） // false IsValidEmail（“a@.com”） // false IsValidEmail（“a@bcom”） // false IsValidEmail（“a.b@com”） // false IsValidEmail（“a@b.”） // false IsValidEmail（“a b@c.com”） // false IsValidEmail（“a@b c.com”） // false IsValidEmail（“a@b.com”） // true IsValidEmail（“a@b.c.com”） // true IsValidEmail（“a+b@c.com”） // true IsValidEmail（“a@123.45.67.89”） // true

它意味着简单，因此它不处理罕见的情况，如电子邮件的括号域包含空格(通常是允许的)，电子邮件的IPv6地址等。

private static bool IsValidEmail(string emailAddress)
{
    const string validEmailPattern = @"^(?!\.)(""([^""\r\\]|\\[""\r\\])*""|"
                                     + @"([-a-z0-9!#$%&'*+/=?^_`{|}~]|(?<!\.)\.)*)(?<!\.)"
                                     + @"@[a-z0-9][\w\.-]*[a-z0-9]\.[a-z][a-z\.]*[a-z]$";

    return new Regex(validEmailPattern, RegexOptions.IgnoreCase).IsMatch(emailAddress);
}

以前，我写了一个EmailAddressValidationAttribute，它应该正确地验证表单中几乎任何相对正常的电子邮件地址

local-part@domain

它是System.ComponentModel.DataAnnotations。ValidationAttribute，所以使用非常简单。

而且，由于挖掘所有rfc和勘误表，并组装所需的所有位来正确枚举所有规则……太乏味了!-我在回答c#电子邮件地址验证源代码的问题时发布了验证器的源代码。

我的验证器无论怎么想象都不是完美的，只是对于初学者来说，它没有任何内置的对发出客户端javascript验证的支持，尽管将其添加进来并不太难。从我上面的回答来看:

Here's the validation attribute I wrote. It validates pretty much every "raw" email address, that is those of the form local-part@domain. It doesn't support any of the other, more...creative constructs that the RFCs allow (this list is not comprehensive by any means): comments (e.g., jsmith@whizbang.com (work)) quoted strings (escaped text, to allow characters not allowed in an atom) domain literals (e.g. foo@[123.45.67.012]) bang-paths (aka source routing) angle addresses (e.g. John Smith <jsmith@whizbang.com>) folding whitespace double-byte characters in either local-part or domain (7-bit ASCII only). etc. It should accept almost any email address that can be expressed thusly foo.bar@bazbat.com without requiring the use of quotes ("), angle brackets ('<>') or square brackets ([]). No attempt is made to validate that the rightmost dns label in the domain is a valid TLD (top-level domain). That is because the list of TLDs is far larger now than the "big 6" (.com, .edu, .gov, .mil, .net, .org) plus 2-letter ISO country codes. ICANN actually updates the TLD list daily, though I suspect that the list doesn't actually change daily. Further, [ICANN just approved a big expansion of the generic TLD namespace][2]). And some email addresses don't have what you'd recognize as a TLD (did you know that postmaster@. is theoretically valid and mailable? Mail to that address should get delivered to the postmaster of the DNS root zone.) Extending the regular expression to support domain literals shouldn't be too difficult.

短而准确的代码

string Email = txtEmail.Text;
if (Email.IsValidEmail())
{
   //use code here 
}

public static bool IsValidEmail(this string email)
{
  string pattern = @"^(?!\.)(""([^""\r\\]|\\[""\r\\])*""|" + @"([-a-z0-9!#$%&'*+/=?^_`{|}~]|(?<!\.)\.)*)(?<!\.)" + @"@[a-z0-9][\w\.-]*[a-z0-9]\.[a-z][a-z\.]*[a-z]$";    
  var regex = new Regex(pattern, RegexOptions.IgnoreCase);    
  return regex.IsMatch(email);
}

我经常用这个来验证电子邮件，它就像一个魅力。这验证了电子邮件必须在@之前至少有一个字符，并且在“”之前至少有一个字符。

public static bool ValidateEmail(string value, bool required, int minLength, int maxLength)
        {
           value = value.Trim();
           if (required == false && value == "") return true;
           if (required && value == "") return false;
           if (value.Length < minLength || value.Length > maxLength) return false;

           //Email must have at least one character before an @, and at least one character before the .
           int index = value.IndexOf('@');
           if (index < 1 || value.LastIndexOf('.') < index + 2) return false;
           return true;
        }

来自@齿轮的投票最多的答案是最好的答案，但我已经尝试实现trim()字符串方法，因此它将从字符串开始到结束修剪所有用户空白。检查代码下面的完整示例-

bool IsValidEmail(string email)
{
    try
    {
        email = email.Trim();
        var addr = new System.Net.Mail.MailAddress(email);
        return addr.Address == email;
    }
    catch
    {
        return false;
    }
}