我只是想指出，最近在. net文档中增加了关于电子邮件验证的内容，也使用了Regex操作。 关于它们实现的详细解释可以在那里找到。

https://learn.microsoft.com/en-us/dotnet/standard/base-types/how-to-verify-that-strings-are-in-valid-email-format

为了方便起见，下面是他们的测试结果:

//       Valid: david.jones@proseware.com
//       Valid: d.j@server1.proseware.com
//       Valid: jones@ms1.proseware.com
//       Invalid: j.@server1.proseware.com
//       Valid: j@proseware.com9
//       Valid: js#internal@proseware.com
//       Valid: j_9@[129.126.118.1]
//       Invalid: j..s@proseware.com
//       Invalid: js*@proseware.com
//       Invalid: js@proseware..com
//       Valid: js@proseware.com9
//       Valid: j.s@server1.proseware.com
//       Valid: "j\"s\""@proseware.com
//       Valid: js@contoso.中国

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]

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。

我根据维基百科的规则和样本地址创建了一个电子邮件地址验证程序。对于那些不介意多看一点代码的人，这里。说实话，我不知道电子邮件地址规范中有这么多疯狂的规则。我没有完全验证主机名或ipaddress，但它仍然通过了维基百科上的所有测试用例。

using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace EmailValidateUnitTests
{
    [TestClass]
    public class EmailValidationUnitTests
    {
        [TestMethod]
        public void TestEmailValidate()
        {
            // Positive Assertions
            Assert.IsTrue("prettyandsimple@example.com".IsValidEmailAddress());
            Assert.IsTrue("very.common@example.com".IsValidEmailAddress());
            Assert.IsTrue("disposable.style.email.with+symbol@example.com".IsValidEmailAddress());
            Assert.IsTrue("other.email-with-dash@example.com".IsValidEmailAddress());
            Assert.IsTrue("\"much.more unusual\"@example.com".IsValidEmailAddress());
            Assert.IsTrue("\"very.unusual.@.unusual.com\"@example.com".IsValidEmailAddress()); //"very.unusual.@.unusual.com"@example.com
            Assert.IsTrue("\"very.(),:;<>[]\\\".VERY.\\\"very@\\\\ \\\"very\\\".unusual\"@strange.example.com".IsValidEmailAddress()); //"very.(),:;<>[]\".VERY.\"very@\\ \"very\".unusual"@strange.example.com
            Assert.IsTrue("admin@mailserver1".IsValidEmailAddress());
            Assert.IsTrue("#!$%&'*+-/=?^_`{}|~@example.org".IsValidEmailAddress());
            Assert.IsTrue("\"()<>[]:,;@\\\\\\\"!#$%&'*+-/=?^_`{}| ~.a\"@example.org".IsValidEmailAddress()); //"()<>[]:,;@\\\"!#$%&'*+-/=?^_`{}| ~.a"@example.org
            Assert.IsTrue("\" \"@example.org".IsValidEmailAddress()); //" "@example.org (space between the quotes)
            Assert.IsTrue("example@localhost".IsValidEmailAddress());
            Assert.IsTrue("example@s.solutions".IsValidEmailAddress());
            Assert.IsTrue("user@com".IsValidEmailAddress());
            Assert.IsTrue("user@localserver".IsValidEmailAddress());
            Assert.IsTrue("user@[IPv6:2001:db8::1]".IsValidEmailAddress());
            Assert.IsTrue("user@[192.168.2.1]".IsValidEmailAddress());
            Assert.IsTrue("(comment and stuff)joe@gmail.com".IsValidEmailAddress());
            Assert.IsTrue("joe(comment and stuff)@gmail.com".IsValidEmailAddress());
            Assert.IsTrue("joe@(comment and stuff)gmail.com".IsValidEmailAddress());
            Assert.IsTrue("joe@gmail.com(comment and stuff)".IsValidEmailAddress());

            // Failure Assertions
            Assert.IsFalse("joe(fail me)smith@gmail.com".IsValidEmailAddress());
            Assert.IsFalse("joesmith@gma(fail me)il.com".IsValidEmailAddress());
            Assert.IsFalse("joe@gmail.com(comment and stuff".IsValidEmailAddress());
            Assert.IsFalse("Abc.example.com".IsValidEmailAddress());
            Assert.IsFalse("A@b@c@example.com".IsValidEmailAddress());
            Assert.IsFalse("a\"b(c)d,e:f;g<h>i[j\\k]l@example.com".IsValidEmailAddress()); //a"b(c)d,e:f;g<h>i[j\k]l@example.com
            Assert.IsFalse("just\"not\"right@example.com".IsValidEmailAddress()); //just"not"right@example.com
            Assert.IsFalse("this is\"not\\allowed@example.com".IsValidEmailAddress()); //this is"not\allowed@example.com
            Assert.IsFalse("this\\ still\\\"not\\\\allowed@example.com".IsValidEmailAddress());//this\ still\"not\\allowed@example.com
            Assert.IsFalse("john..doe@example.com".IsValidEmailAddress());
            Assert.IsFalse("john.doe@example..com".IsValidEmailAddress());
            Assert.IsFalse(" joe@gmail.com".IsValidEmailAddress());
            Assert.IsFalse("joe@gmail.com ".IsValidEmailAddress());
        }
    }

    public static class ExtensionMethods
    {
        private const string ValidLocalPartChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!#$%&'*+-/=?^_`{|}~";
        private const string ValidQuotedLocalPartChars = "(),:;<>@[]. ";
        private const string ValidDomainPartChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-:";

        private enum EmailParseMode
        {
            BeginLocal, Local, QuotedLocalEscape, QuotedLocal, QuotedLocalEnd, LocalSplit, LocalComment,
            At,
            Domain, DomainSplit, DomainComment, BracketedDomain, BracketedDomainEnd
        };

        public static bool IsValidEmailAddress(this string s)
        {
            bool valid = true;

            bool hasLocal = false, hasDomain = false;
            int commentStart = -1, commentEnd = -1;
            var mode = EmailParseMode.BeginLocal;
            for (int i = 0; i < s.Length; i++)
            {
                char c = s[i];
                if (mode == EmailParseMode.BeginLocal || mode == EmailParseMode.LocalSplit)
                {
                    if (c == '(') { mode = EmailParseMode.LocalComment; commentStart = i; commentEnd = -1; }
                    else if (c == '"') { mode = EmailParseMode.QuotedLocal; }
                    else if (ValidLocalPartChars.IndexOf(c) >= 0) { mode = EmailParseMode.Local; hasLocal = true; }
                    else { valid = false; break; }
                }
                else if (mode == EmailParseMode.LocalComment)
                {
                    if (c == ')')
                    {
                        mode = EmailParseMode.Local; commentEnd = i;
                        // comments can only be at beginning and end of parts...
                        if (commentStart != 0 && ((commentEnd + 1) < s.Length) && s[commentEnd + 1] != '@') { valid = false; break; }
                    }
                }
                else if (mode == EmailParseMode.Local)
                {
                    if (c == '.') mode = EmailParseMode.LocalSplit;
                    else if (c == '@') mode = EmailParseMode.At;
                    else if (c == '(') { mode = EmailParseMode.LocalComment; commentStart = i; commentEnd = -1; }
                    else if (ValidLocalPartChars.IndexOf(c) >= 0) { hasLocal = true; }
                    else { valid = false; break; }
                }
                else if (mode == EmailParseMode.QuotedLocal)
                {
                    if (c == '"') { mode = EmailParseMode.QuotedLocalEnd; }
                    else if (c == '\\') { mode = EmailParseMode.QuotedLocalEscape; }
                    else if (ValidLocalPartChars.IndexOf(c) >= 0 || ValidQuotedLocalPartChars.IndexOf(c) >= 0) { hasLocal = true; }
                    else { valid = false; break; }
                }
                else if (mode == EmailParseMode.QuotedLocalEscape)
                {
                    if (c == '"' || c == '\\') { mode = EmailParseMode.QuotedLocal; hasLocal = true; }
                    else { valid = false; break; }
                }
                else if (mode == EmailParseMode.QuotedLocalEnd)
                {
                    if (c == '.') { mode = EmailParseMode.LocalSplit; }
                    else if (c == '@') mode = EmailParseMode.At;
                    else if (c == '(') { mode = EmailParseMode.LocalComment; commentStart = i; commentEnd = -1; }
                    else { valid = false; break; }
                }
                else if (mode == EmailParseMode.At)
                {
                    if (c == '[') { mode = EmailParseMode.BracketedDomain; }
                    else if (c == '(') { mode = EmailParseMode.DomainComment; commentStart = i; commentEnd = -1; }
                    else if (ValidDomainPartChars.IndexOf(c) >= 0) { mode = EmailParseMode.Domain; hasDomain = true; }
                    else { valid = false; break; }
                }
                else if (mode == EmailParseMode.DomainComment)
                {
                    if (c == ')')
                    {
                        mode = EmailParseMode.Domain;
                        commentEnd = i;
                        // comments can only be at beginning and end of parts...
                        if ((commentEnd + 1) != s.Length && (commentStart > 0) && s[commentStart - 1] != '@') { valid = false; break; }
                    }
                }
                else if (mode == EmailParseMode.DomainSplit)
                {
                    if (ValidDomainPartChars.IndexOf(c) >= 0) { mode = EmailParseMode.Domain; hasDomain = true; }
                    else { valid = false; break; }
                }
                else if (mode == EmailParseMode.Domain)
                {
                    if (c == '(') { mode = EmailParseMode.DomainComment; commentStart = i; commentEnd = -1; }
                    else if (c == '.') { mode = EmailParseMode.DomainSplit; }
                    else if (ValidDomainPartChars.IndexOf(c) >= 0) { hasDomain = true; }
                    else { valid = false; break; }
                }
                else if (mode == EmailParseMode.BracketedDomain)
                {
                    if (c == ']') { mode = EmailParseMode.BracketedDomainEnd; }
                    else if (c == '.' || ValidDomainPartChars.IndexOf(c) >= 0) { hasDomain = true; }
                    else { valid = false; break; }
                }
                else if (mode == EmailParseMode.BracketedDomain)
                {
                    if (c == '(') { mode = EmailParseMode.DomainComment; commentStart = i; commentEnd = -1; }
                    else { valid = false; break; }
                }
            }
            bool unfinishedComment = (commentEnd == -1 && commentStart >= 0);

            return hasLocal && hasDomain && valid && !unfinishedComment;
        }
    }
}

我从第1条中得到Phil的答案，并创建了这个类。 这样调用它:bool isValid = Validator.EmailIsValid(emailString);

下面是这个类:

using System.Text.RegularExpressions;

public static class Validator
{

    static Regex ValidEmailRegex = CreateValidEmailRegex();

    /// <summary>
    /// Taken from http://haacked.com/archive/2007/08/21/i-knew-how-to-validate-an-email-address-until-i.aspx
    /// </summary>
    /// <returns></returns>
    private static Regex CreateValidEmailRegex()
    {
        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);
    }

    internal static bool EmailIsValid(string emailAddress)
    {
        bool isValid = ValidEmailRegex.IsMatch(emailAddress);

        return isValid;
    }
}

我用的是单线法，它对我有用

using System.ComponentModel.DataAnnotations;
public bool IsValidEmail(string source)
{
    return new EmailAddressAttribute().IsValid(source);
}

根据注释，如果源(电子邮件地址)为空，这将“失败”。

public static bool IsValidEmailAddress(this string address) => address != null && new EmailAddressAttribute().IsValid(address);