我写了一个函数来检查电子邮件是否有效。在大多数情况下，这似乎对我很有效。

结果:

dasddas-@.com => FALSE
-asd@das.com => FALSE
as3d@dac.coas- => FALSE
dsq!a?@das.com => FALSE
_dasd@sd.com => FALSE
dad@sds => FALSE
asd-@asd.com => FALSE
dasd_-@jdas.com => FALSE
asd@dasd@asd.cm => FALSE
da23@das..com => FALSE
_dasd_das_@9.com => FALSE

d23d@da9.co9 => TRUE
dasd.dadas@dasd.com => TRUE
dda_das@das-dasd.com => TRUE
dasd-dasd@das.com.das => TRUE

代码:

    private bool IsValidEmail(string email)
    {
        bool valid = false;
        try
        {
            var addr = new System.Net.Mail.MailAddress(email);
            valid = true;
        }
        catch
        {
            valid = false;
            goto End_Func;
        }

        valid = false;
        int pos_at = email.IndexOf('@');
        char checker = Convert.ToChar(email.Substring(pos_at + 1, 1));
        var chars = "qwertyuiopasdfghjklzxcvbnm0123456789";
        foreach (char chr in chars)
        {
            if (checker == chr)
            {
                valid = true;
                break;
            }
        }
        if (valid == false)
        {
            goto End_Func;
        } 

        int pos_dot = email.IndexOf('.', pos_at + 1);
        if(pos_dot == -1)
        {
            valid = false;
            goto End_Func;
        }

        valid = false;
        try
        {
            checker = Convert.ToChar(email.Substring(pos_dot + 1, 1));
            foreach (char chr in chars)
            {
                if (checker == chr)
                {
                    valid = true;
                    break;
                }
            }
        }
        catch
        {
            valid = false;
            goto End_Func;
        }

        Regex valid_checker = new Regex(@"^[a-zA-Z0-9_@.-]*$");
        valid = valid_checker.IsMatch(email);
        if (valid == false)
        {
            goto End_Func;
        }

        List<int> pos_list = new List<int> { };
        int pos = 0;
        while (email.IndexOf('_', pos) != -1)
        {
            pos_list.Add(email.IndexOf('_', pos));
            pos = email.IndexOf('_', pos) + 1;
        }

        pos = 0;
        while (email.IndexOf('.', pos) != -1)
        {
            pos_list.Add(email.IndexOf('.', pos));
            pos = email.IndexOf('.', pos) + 1;
        }

        pos = 0;
        while (email.IndexOf('-', pos) != -1)
        {
            pos_list.Add(email.IndexOf('-', pos));
            pos = email.IndexOf('-', pos) + 1;
        }

        int sp_cnt = pos_list.Count();
        pos_list.Sort();
        for (int i = 0; i < sp_cnt - 1; i++)
        {
            if (pos_list[i] + 1 == pos_list[i + 1])
            {
                valid = false;
                break;
            }

            if (pos_list[i]+1 == pos_at || pos_list[i]+1 == pos_dot)
            {
                valid = false;
                break;
            }
        }

        if(valid == false)
        {
            goto End_Func;
        }

        if (pos_list[sp_cnt - 1] == email.Length - 1 || pos_list[0] == 0)
        {
            valid = false;
        }

    End_Func:;
        return valid;
    }

Personally, I would say that you should just make sure there is an @ symbol in there, with possibly a . character. There's many regexes you could use of varying correctness, but I think most of these leave out valid email addresses, or let invalid ones through. If people want to put in a fake email address, they will put in a fake one. If you need to verify that the email address is legit, and that the person is in control of that email address, then you will need to send them an email with a special coded link so they can verify that it indeed is a real address.

我将Poyson 1的答案简化如下:

public static bool IsValidEmailAddress(string candidateEmailAddr)
{
    string regexExpresion = "\\w+([-+.']\\w+)*@\\w+([-.]\\w+)*\\.\\w+([-.]\\w+)*";
    return (Regex.IsMatch(candidateEmailAddr, regexExpresion)) && 
           (Regex.Replace(candidateEmailAddr, regexExpresion, string.Empty).Length == 0);
}

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;
    }
}

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;
    }
}

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);
}