What could cause a message sent from Gmail SMTP using C# not to arrive - No exception is thrown

Question

I am trying to send mail through my Google Apps email account. This is setup on my own domain and is all working fine through the web interface and through outlook.

However, i'm trying to send an email from a webpage using C#, I get no exceptions and everything appears to go smoothly, but the emails never seem to arrive:

MailMessage msg = new MailMessage("no-reply@xxxx.co.uk", "dan@xxxx.co.uk");
    SmtpClient smtp = new SmtpClient("smtp.gmail.com", 587);
    smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
    smtp.Credentials = new NetworkCredential("no-reply@xxxx.co.uk", "xxxxxxxxx");
    smtp.EnableSsl = true;
    msg.IsBodyHtml = true;
    msg.Body = body;

    smtp.Send(msg);

The body is a string which i've generated earlier in the code. As far as i'm aware, if there was a problem with actually connecting to the SMTP server at Gmail then I would get an exception thrown.

Any ideas what could cause this not to work? Only thing different I can see compared to other peoples examples is that I have set body as HTML and i'm sending from a Google Apps account rather than an @gmail.com account.

The google apps itself is all configured fully and working, i've set this up numerous times so I know it's not likely to be a problem there.

I also tried sending on port 25, as that's what you use when configuring Outlook to send from a Gmail account.

Same result for both, no exception thrown, but email never arrives. Both emails the sender and receiver are on my domain using Google Apps for Gmail.

EDIT:

Also I should mention that I have signed in using both accounts, and both have IMAP and POP enabled in their settings etc.

New findings

This is a strange one

If I send mail manually from:

no-reply@mydomain.com to dan@mydomain.com - Then it works

But if I send it through code this way...it doesn't work...

If I send the following through code it does work:

no-reply@mydomain.com to me@gmail.com or me@ntlworld.com - This works through code!

I would then be led to think that this means a problem with dan@mydomain.com receiving messages...But it receives any messages sent manually from any google, hotmail, or ntlworld email address i've tried.

So either Google Apps accounts can't receive email sent through code (unlikely) or something else is at play here

Answer 1

The server may silently discard your message if there is a problem with it. - Despite any spec saying otherwise.

The message might be lost in the ether despite being "delivered".

The SMTP server may be applying severe filtering and might additionally require that your sender and destination email addresses match up 'correctly'

I suggest trying with a different SMTP host just to check. :)

Answer 2

Dan, Check this out Sending email through Gmail SMTP server with C#

Hope this helps

Answer 3

When you setup Google Apps, even if the MX records are all working correctly for sending mail manually to/from other accounts, there can still be problems.

The answer is to wait 12-24 hours after setting up your MX Records, even if everything else is working fine.

If you receive no exception, then to me this is the only answer at the moment.

All is working correctly now. Even though all MX records were correct on my DNS and email appeared to be working, there were still changes going on in the background