Send mail using yahoo in ASP.Net

Question

I have a web server at home running IIS 10 and .Net 4.8.

I am trying to send an email through a C#.Net, using the following yahoo stmp service call.

However, I cannot seem to get it to work? Whenever I try to execute the following code, the web page seems to be loading for about 30 seconds, then returns an "SMTP Server returned an invalid response" error message, which apparently doesn't mean anything specific? This is getting pretty frustrating as I've been on this for over 4 hours now... so thanks for any help!

using (MailMessage mm = new MailMessage("uneviesystems@yahoo.com", "MaxOvrdrv007@yahoo.ca"))
{
    mm.Subject = "test";
    mm.Body = "testing maudine...";
    mm.IsBodyHtml = false;
    SmtpClient smtp = new SmtpClient();
    smtp.Host = "smtp.mail.yahoo.com";
    smtp.EnableSsl = true;
    
    NetworkCredential NetworkCred = new NetworkCredential("uneviesystems@yahoo.com", "*******");
    smtp.UseDefaultCredentials = true;
    smtp.Credentials = NetworkCred;
    smtp.Port = 465;
    try
    {
        smtp.Send(mm);
    }
    catch(SmtpException ex)
    {
        string p = "";
    }
            
}

Answer 1

try using application password instead account password. You can generate application password in account settings.

Answer 2

Port 465 isn't supported by System.Net.Mail.SmtpClient -

http://msdn.microsoft.com/en-us/library/system.net.mail.smtpclient.enablessl.aspx

You could try using port 587 instead (if Yahoo supports it) and disable SSL.

Answer 3

Send your email asynchronously and format your code to dispose client properly.

using (var message = new MailMessage())
{
    message.To.Add(new MailAddress("recepient email", "receipient name"));
    message.From = new MailAddress("your email", "your name");
    message.Subject = "My subject";
    message.Body = "My message";
    message.IsBodyHtml = false; // change to true if body msg is in html

    using (var client = new SmtpClient("smtp.mail.yahoo.com"))
    {
        client.UseDefaultCredentials = false;
        client.Port = 587;
        client.Credentials = new NetworkCredential("your email", "your password");
        client.EnableSsl = true;

        try
        {
            await client.SendMailAsync(message); // Email sent
        }
        catch (Exception e)
        {
            // Email not sent, log exception
        }
    }
}