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using System.Net.Mail;
using System.Diagnostics;

public static bool checkMXRecords(string email) 
    {
        MailAddress addr = new MailAddress(email);
        string domain = addr.Host;

        string command = "nslookup -querytype=mx " + domain;
        ProcessStartInfo procStartInfo = new ProcessStartInfo("cmd", "/c " + command);

        procStartInfo.RedirectStandardOutput = true;
        procStartInfo.UseShellExecute = false;

        procStartInfo.CreateNoWindow = true;

        Process proc = new Process();
        proc.StartInfo = procStartInfo;
        proc.Start();
        string result = proc.StandardOutput.ReadToEnd();

        if (result.ToLower().Contains("mail exchanger"))
        {
            return true;
        }
        else return false;

     } // checkMXRecords

using System.Net.Mail;
using System.Diagnostics;

public static bool checkMXRecords(string email) 
    {
        MailAddress addr = new MailAddress(email);
        string domain = addr.Host;

        string command = "nslookup -querytype=mx " + domain;
        ProcessStartInfo procStartInfo = new ProcessStartInfo("cmd", "/c " + command);

        procStartInfo.RedirectStandardOutput = true;
        procStartInfo.UseShellExecute = false;

        procStartInfo.CreateNoWindow = true;

        Process proc = new Process();
        proc.StartInfo = procStartInfo;
        proc.Start();
        string result = proc.StandardOutput.ReadToEnd();

        if (result.ToLower().Contains("mail exchanger"))
        {
            return true;
        }
        else return false;

     } // checkMXRecords

Here is my C# code to use nslookup to verify whether an email domain has valid MX records. Runs quick and ok on Win 2008 R2 and Win 7.

using System.Net.Mail;
using System.Diagnostics;

public static bool checkMXRecords(string email) 
    {
        MailAddress addr = new MailAddress(email);
        string domain = addr.Host;

        string command = "nslookup -querytype=mx " + domain;
        ProcessStartInfo procStartInfo = new ProcessStartInfo("cmd", "/c " + command);

        procStartInfo.RedirectStandardOutput = true;
        procStartInfo.UseShellExecute = false;

        procStartInfo.CreateNoWindow = true;

        Process proc = new Process();
        proc.StartInfo = procStartInfo;
        proc.Start();
        string result = proc.StandardOutput.ReadToEnd();

        if (result.ToLower().Contains("mail exchanger"))
        {
            return true;
        }
        else return false;

     } // checkMXRecords

another option is to use the Arsofttools nuget package but it may be slow on Windows Server 2008 R2 as I have experienced but runs quick on Win 7.

The three main levels of email validation:

1. regular expression check for a properly formatted email address [email protected]

2. email domain check against MX records to see if the domain name has an email service

3. sending a confirmation email with a confirmation link or code

Level 1:

In Visual Studio, you can use the "Regular Expression Validator". And in the "ValidationExpression" property you can click on the "..." button that has a wizard to add in the regular expression format for email addresses.

Level 2:

Here is my C# code below to use nslookup to verify whether an email domain has valid MX records. Runs quick and ok on Win 2008 R2 and Win 7.

using System.Net.Mail;
using System.Diagnostics;

public static bool checkMXRecords(string email) 
    {
        MailAddress addr = new MailAddress(email);
        string domain = addr.Host;

        string command = "nslookup -querytype=mx " + domain;
        ProcessStartInfo procStartInfo = new ProcessStartInfo("cmd", "/c " + command);

        procStartInfo.RedirectStandardOutput = true;
        procStartInfo.UseShellExecute = false;

        procStartInfo.CreateNoWindow = true;

        Process proc = new Process();
        proc.StartInfo = procStartInfo;
        proc.Start();
        string result = proc.StandardOutput.ReadToEnd();

        if (result.ToLower().Contains("mail exchanger"))
        {
            return true;
        }
        else return false;

     } // checkMXRecords

another option is to use the Arsofttools nuget package but it may be slow on Windows Server 2008 R2 as I have experienced but runs quick on Win 7.

Level 3:

For email confirmation, you can either generate an email specific hex url (using encryption functions) etc http://domain.com/validateEmail?code=abcd1234 to validate the email address when the user clicks on it. There is no need to store this url in memory.

Here is my C# code to use nslookup to verify whether an email domain has valid MX records. Runs quick and ok on Win 2008 R2 and Win 7.

using System.Net.Mail; using System.Diagnostics;

public static bool checkMXRecords(string email) { MailAddress addr = new MailAddress(email); string domain = addr.Host;

        string command = "nslookup -querytype=mx " + domain;
        ProcessStartInfo procStartInfo = new ProcessStartInfo("cmd", "/c " + command);

        procStartInfo.RedirectStandardOutput = true;
        procStartInfo.UseShellExecute = false;

        procStartInfo.CreateNoWindow = true;

        Process proc = new Process();
        proc.StartInfo = procStartInfo;
        proc.Start();
        string result = proc.StandardOutput.ReadToEnd();

        if (result.ToLower().Contains("mail exchanger"))
        {
            return true;
        }
        else return false;

     } // checkMXRecords

another option is to use the Arsofttools nuget package but it may be slow on Windows Server 2008 R2 as I have experienced but runs quick on Win 7.

Here is my C# code to use nslookup to verify whether an email domain has valid MX records. Runs quick and ok on Win 2008 R2 and Win 7.

using System.Net.Mail;
using System.Diagnostics;

public static bool checkMXRecords(string email) 
    {
        MailAddress addr = new MailAddress(email);
        string domain = addr.Host;

        string command = "nslookup -querytype=mx " + domain;
        ProcessStartInfo procStartInfo = new ProcessStartInfo("cmd", "/c " + command);

        procStartInfo.RedirectStandardOutput = true;
        procStartInfo.UseShellExecute = false;

        procStartInfo.CreateNoWindow = true;

        Process proc = new Process();
        proc.StartInfo = procStartInfo;
        proc.Start();
        string result = proc.StandardOutput.ReadToEnd();

        if (result.ToLower().Contains("mail exchanger"))
        {
            return true;
        }
        else return false;

     } // checkMXRecords

another option is to use the Arsofttools nuget package but it may be slow on Windows Server 2008 R2 as I have experienced but runs quick on Win 7.