An existing connection was forcibly closed by the remote host in SMTP client

Question

I am about to give up debugging SMTP servers to send email... My code is the following

 SmtpClient mailClient = new SmtpClient("plus.smtp.mail.yahoo.com", 465);
    mailClient.EnableSsl = true;
    MailMessage message = new MailMessage();
    message.To.Add("aditya15417@hotmail.com");
    message.Subject = "permias-tucson-contact-us";
    mailClient.Credentials = new NetworkCredential("myemail@yahoo.com", "mypassword");
    MailAddress fromAddress = new MailAddress(Email.Text, Name.Text);
    message.From = fromAddress;

    mailClient.Send(message);

You cannot send emails without logging in to an SMTP server with a username and password. You should probably create a separate email account to send from. — SLaks, Apr 04 '10 at 21:45
I did that...updated the code above and it still gives the same error — aherlambang, Apr 04 '10 at 23:35
I am having the same issue, but intermittently. For example when looping through 3000 recipients and sending out 3000 emails, it will throw this error randomly on say 100 of the emails that go out, but the rest will go fine. It can happen just when sending one single email out by itself too. Emails are behaving very unreliably for me and I don't know what else I can do to debut it either. Any luck at your end?? — Aaron, Feb 18 '11 at 09:42

score 1 · Accepted Answer · answered Apr 04 '10 at 21:42

1

You need to pass login credentials:

mailClient.Credentials = new NetworkCredential(Email.Text, password)

answered Apr 04 '10 at 21:42

SLaks

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so I should know what the sender's password is?? – aherlambang Apr 04 '10 at 22:59
Yes you'll need the username and password. In the case of Yahoo I think the username would be the email address. If the SMTP didn't require authentication then anyone could use it for sending spam. – Dalbir Singh Apr 04 '10 at 23:09
No I don't believe credentials are the issue. With or without credentials, this problem can intermittently occur. – Aaron Feb 18 '11 at 09:40
1

@Aaron: THat's a server issue. – SLaks Feb 18 '11 at 12:14

score 1 · Answer 2 · answered Sep 11 '10 at 13:39

Here's a full working example:

public class Program
{
    static void Main(string[] args)
    {
        using (var client = new SmtpClient("smtp.mail.yahoo.com", 587))
        {
            client.Credentials = new NetworkCredential("youraccount@yahoo.com", "secret");
            var mail = new MailMessage();
            mail.From = new MailAddress("youraccount@yahoo.com");
            mail.To.Add("destaccount@gmail.com");
            mail.Subject = "Test mail";
            mail.Body = "test body";
            client.Send(mail);
        }
    }
}

Make sure you replace your account and password.

An existing connection was forcibly closed by the remote host in SMTP client

2 Answers2

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