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.

    /// <summary>
    /// Validates the email if it follows the valid email format
    /// </summary>
    /// <param name="emailAddress"></param>
    /// <returns></returns>
    public static bool EmailIsValid(string emailAddress)
    {
        //if string is not null and empty then check for email follow the format
        return string.IsNullOrEmpty(emailAddress)?false : new Regex(@"^(?!\.)(""([^""\r\\]|\\[""\r\\])*""|([-a-z0-9!#$%&'*+/=?^_`{|}~]|(?<!\.)\.)*)(?<!\.)@[a-z0-9][\w\.-]*[a-z0-9]\.[a-z][a-z\.]*[a-z]$", RegexOptions.IgnoreCase).IsMatch(emailAddress);
    }

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);
}

我发现这个正则表达式在检查@标记以外的东西和接受奇怪的边缘情况之间是一个很好的权衡:

^[^@\s]+@[^@\s]+(\.[^@\s]+)+$

它至少会让你在@标记周围放一些东西，并且至少放一个正常的域。

电子邮件地址验证并不像看起来那么简单。实际上，从理论上讲，仅使用正则表达式完全验证电子邮件地址是不可能的。

请查看我的博客文章，了解关于这个主题的讨论以及使用FParsec的f#实现。[/ shameless_plug]

There are a lot of strong answers here. However, I recommend that we take a step back. @Cogwheel answers the question https://stackoverflow.com/a/1374644/388267. Nevertheless, it could be costly in a bulk validation scenario, if many of the email address being validated are invalid. I suggest that we employ a bit of logic before we enter into his try-catch block. I know that the following code could be written using RegEx but that could be costly for new developers to understand. This is my twopence worth:

    public static bool IsEmail(this string input)
    {
        if (string.IsNullOrWhiteSpace(input)) return false;

        // MUST CONTAIN ONE AND ONLY ONE @
        var atCount = input.Count(c => c == '@');
        if (atCount != 1) return false;

        // MUST CONTAIN PERIOD
        if (!input.Contains(".")) return false;

        // @ MUST OCCUR BEFORE LAST PERIOD
        var indexOfAt = input.IndexOf("@", StringComparison.Ordinal);
        var lastIndexOfPeriod = input.LastIndexOf(".", StringComparison.Ordinal);
        var atBeforeLastPeriod = lastIndexOfPeriod > indexOfAt;
        if (!atBeforeLastPeriod) return false;

        // CODE FROM COGWHEEL'S ANSWER: https://stackoverflow.com/a/1374644/388267 
        try
        {
            var addr = new System.Net.Mail.MailAddress(input);
            return addr.Address == input;
        }
        catch
        {
            return false;
        }
    }