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;
    }
}

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);
}

老实说，在产品代码中，我所做的最好的事情就是检查@符号。

我从来没有在一个地方完全验证电子邮件。你知道我怎么判断它是否有效吗?如果发送出去了。如果没有，那就糟了，如果有，生活就好了。这就是我需要知道的。

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);
}

.net 4.5增加了System.ComponentModel.DataAnnotations.EmailAddressAttribute

你可以浏览EmailAddressAttribute的源代码，这是它内部使用的正则表达式:

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])))\.?$";

最优雅的方法是使用. net的内置方法。

这些方法:

都是经过考验的。我在自己的专业项目中使用了这些方法。 内部使用正则表达式，这是可靠和快速的。 由微软为c#编写。没有必要做重复的工作。 返回bool类型的结果。True表示邮件有效。

适用于。net 4.5及以上版本的用户

将此引用添加到项目中:

System.ComponentModel.DataAnnotations

现在你可以使用下面的代码:

(new EmailAddressAttribute().IsValid("youremailhere@test.test"));

使用实例

下面是一些需要声明的方法:

protected List<string> GetRecipients() // Gets recipients from TextBox named `TxtRecipients`
{
    List<string> MethodResult = null;

    try
    {
        List<string> Recipients = TxtRecipients.Text.Replace(",",";").Replace(" ", "").Split(';').ToList();

        List<string> RecipientsCleaned = new List<string>();

        foreach (string Recipient in RecipientsCleaned)
        {
            if (!String.IsNullOrWhiteSpace(Recipient))
            {
                RecipientsNoBlanks.Add(Recipient);

            }

        }

        MethodResult = RecipientsNoBlanks;

    }
    catch//(Exception ex)
    {
        //ex.HandleException();
    }

    return MethodResult;

}


public static bool IsValidEmailAddresses(List<string> recipients)
{
    List<string> InvalidAddresses = GetInvalidEmailAddresses(recipients);

    return InvalidAddresses != null && InvalidAddresses.Count == 0;

}

public static List<string> GetInvalidEmailAddresses(List<string> recipients)
{
    List<string> MethodResult = null;

    try
    {
        List<string> InvalidEmailAddresses = new List<string>();

        foreach (string Recipient in recipients)
        {
            if (!(new EmailAddressAttribute().IsValid(Recipient)) && !InvalidEmailAddresses.Contains(Recipient))
            {
                InvalidEmailAddresses.Add(Recipient);

            }

        }

        MethodResult = InvalidEmailAddresses;

    }
    catch//(Exception ex)
    {
        //ex.HandleException();

    }

    return MethodResult;

}

.．.以及演示它们的代码:

List<string> Recipients = GetRecipients();

bool IsValidEmailAddresses = IsValidEmailAddresses(Recipients);

if (IsValidEmailAddresses)
{
    //Emails are valid. Your code here

}
else
{
    StringBuilder sb = new StringBuilder();

    sb.Append("The following addresses are invalid:");

    List<string> InvalidEmails = GetInvalidEmailAddresses(Recipients);

    foreach (string InvalidEmail in InvalidEmails)
    {
        sb.Append("\n" + InvalidEmail);

    }

    MessageBox.Show(sb.ToString());

}

另外，这个例子:

扩展超出规范，因为一个字符串用于包含0，一个或多个由分号分隔的电子邮件地址; 清楚地演示了如何使用EmailAddressAttribute对象的IsValid方法。

对于.Net 4.5以下版本的用户，可以选择

对于.Net 4.5不可用的情况，我使用以下解决方案:

具体来说，我使用:

public static bool IsValidEmailAddress(string emailAddress)
{
    bool MethodResult = false;

    try
    {
        MailAddress m = new MailAddress(emailAddress);

        MethodResult = m.Address == emailAddress;

    }
    catch //(Exception ex)
    {
        //ex.HandleException();

    }

    return MethodResult;

}

public static List<string> GetInvalidEmailAddresses(List<string> recipients)
{
    List<string> MethodResult = null;

    try
    {
        List<string> InvalidEmailAddresses = new List<string>();

        foreach (string Recipient in recipients)
        {
            if (!IsValidEmail(Recipient) && !InvalidEmailAddresses.Contains(Recipient))
            {
                InvalidEmailAddresses.Add(Recipient);

            }

        }

        MethodResult = InvalidEmailAddresses;

    }
    catch //(Exception ex)
    {
        //ex.HandleException();

    }

    return MethodResult;

}