looking for .NET SmtpClient troubleshooting ideas

Question

I have been braining my brains for more than three hours trying everything I can think of to get the .NET4.5 SmtpClient to send a test email.

Things I have tried:

disabling windows firewall

disabling router firewall and enabling DMZ, biggest unknown

disabling antivirus

every possible permutation of port (25,26,465,587) and ssl (enabled/not) setting

watching the application code open a network connection in a connection viewer (the connection never gets past SYN_SENT)

the exception reported is sometimes "The operation has timed out." and sometimes "A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond [ip.ad.re.ss]:587" depending on the settings used.

here is the code I am trying to get to work, it is being run in a Win7Pro IIS7 MVC 4 app:

    string fromaddress = "address@gmail.com";
    string toaddressstring = "recipient@gmail.com";
    string subjecttext = "test";
    string bodytext = "simple test email text";
    System.Net.Mail.MailMessage email = new System.Net.Mail.MailMessage();
    email.IsBodyHtml = true;
    email.Body = "simple test email body text";
    email.From = new System.Net.Mail.MailAddress(fromaddress);
    email.To.Add(toaddressstring);
    email.Subject = subjecttext;
    System.Net.Mail.SmtpClient smtpcli = new System.Net.Mail.SmtpClient();
    smtpcli.Host = "smtp.gmail.com";
    smtpcli.Port = 587;
    smtpcli.Timeout = 10000;
    smtpcli.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;
    smtpcli.EnableSsl = true;
    smtpcli.UseDefaultCredentials = false;
    smtpcli.Credentials = new NetworkCredential(fromaddress, "password");
    smtpcli.Send(email);

I have totally run out of ideas, what else might be wrong? Any suggestions would be fantastic.

Answer 1

Seems that you cannot establish a TCP connection. I tested your code and is working well on my pc.

You can try troubleshooting checklist from google support page Problems sending mail with POP or IMAP

Answer 2

use this code and try to check in different ip from which ur using now.

    var message = new MailMessage();
    message.From = new MailAddress("from@gmail.com");
    MailAddress to = new MailAddress("to@gmail.com");
    message.Subject = "Subject";       
    string bodyString = "";
    bodyString += "Hello";
    message.Body = bodyString;
    message.To.Add(to);
    message.IsBodyHtml = true;
    SmtpClient smtp = new SmtpClient("smtp.gmail.com");
    smtp.Credentials = new System.Net.NetworkCredential("user@gmail.com", "password");
    smtp.EnableSsl = false;
    smtp.Send(message);