Question

On my website i send e-mails. My situation is these mails are being sent when using my local development machine, and not on my production environment.

The web.config is the same on both sites:

  <system.net>
    <mailSettings>
      <smtp from="[e-mail]" deliveryMethod="Network">
        <network host="mail.domain.dk" userName="[e-mail]"  password="mypassword" port="26"></network>
      </smtp>
    </mailSettings>
  </system.net>

In my code, I send it like this:

 SmtpClient client = new SmtpClient();
 client.Send(mail);

I have no idea how to debug this problem, as it is the exactly same code on both production and development.

Any ideas on how to start debugging / solving the problem?

EDIT:

I managed to get a log from the server. Error is:

2012-11-01 20:41:58,383 [11] FATAL GKBusiness.Managers.MailManager [(null)] - Email exception: Mailbox unavailable. The server response was: Access denied - Invalid HELO name (See RFC2821 4.1.1.1)

Hmm

Answer 1

My situation is these mails are being sent when using my local development machine, and not on my production environment.

<network host=..... port="26">

If you are in a shared hosting environment, it’s likely that ASP.Net is set to Medium Trust – and if so, SMTP is restricted to port 25.

It will work in your local environment because ASP.Net is set to Full Trust (in local/VS dev).