Can't send mail from C#

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When I send an email from c# I get a "relay access denied" error.
Using the same credentials from Thunderbird everything works fine.
I run my own mail server with Postfix and Dovecote.

Below is my code:

C#

System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient();
    client.Host = "mail.mydomainname.nl";
    client.Port = 2525;
    client.Credentials = new System.Net.NetworkCredential("username@mydomainname.nl", "correctpassword");
    client.UseDefaultCredentials = false;

string Van = "username@mydomainname.nl";


System.Net.Mail.MailMessage msg = new System.Net.Mail.MailMessage("username@mydomainname.nl", "somebody@hisdomainname.nl", "Subject of this mail", "Contents of this mail");

try
{
    client.Send(msg);
}
catch(Exception e)
{
    System.Windows.Forms.MessageBox.Show("Error sending email: \r\n" + e.Message );
    return false;
}

return true;

Thanks in advance,

Rob

Edit 2012-12-04:
I currently use the myNetworks entry in /etc/postfix/main.cf to add the IP from which I'm sending. This ain't ideal for several reasons so I'm still looking for a better solution.

Rob

Posted 4-Aug-12 17:25pm

RobScripta

Updated 3-Dec-12 23:23pm

v2

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Dave Kreskowiak · Answer 1 · 2012-08-04T17:34:00

Solution 1

"Relay access denied" usually means the server you're using to send the email doesn't like the domain in the From field of the email. Are you trying to send an email as a user from a different domain than the SMTP server you're using to send it?? For example, using a Google SMTP server to send an email with a From address like someuser@yahoo.com.

Posted 4-Aug-12 17:34pm

Dave Kreskowiak

Updated 4-Aug-12 17:35pm

v2

Comments

Sandeep Mewara 5-Aug-12 2:55am

Comment from OP:
No, it's the same domain.
I use exactly the same data from thunderbird, and it works OK.
I feel it has something to do with authentication.

Rob

azizulhoque.bd · Answer 2 · 2012-12-04T00:24:00

Hi dear,

Check this solution.

private void MailSend()
       {
           try
           {
               MailMessage mail = new MailMessage();
               SmtpClient SmtpServer = new SmtpClient("smtp.gmail.com");
               SmtpServer.Host = "smtp.gmail.com";

               mail.From = new MailAddress("FromMailName@gamil.com");
               mail.To.Add("ToMailName@gmail.com");
               mail.Subject = "Test Mail";
               mail.Body = "This is for testing SMTP mail from GMAIL";

               SmtpServer.Port = 587;

               SmtpServer.Credentials = new System.Net.NetworkCredential("ToMailName@gmail.com", "123456"); // User Mail Name And Mail Password
               SmtpServer.EnableSsl = true;

               SmtpServer.Send(mail);
           }
           catch (Exception ex)
           {
               MessageBox.Show(ex.ToString());
           }
       }