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SMTP Problems

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I am trying to send a mail message using smtp and I keep getting this error.

"Error sending mail! System.web.HTTPExeption : Could not access 'CDO Message


"The server response was 421 4.4.1, unable to contact

I think the above refers to the firewall but I do not understand anything
about firewalls.
When I run the code on my development machine it works great.

The SMTP server is set to local host.

Any Ideas. This is doing my head in and our server guy has no idea.

Thanks in Advance

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System.Web.Mail is actually a wrapper around the COM dlls CDOSys.dll and CDONTS.dll. So, all programming exceptions are actually COM exceptions and are usually generated because there is either a problem accessing the CDOSys.dll or CDONTS.dll, or else these dlls are not installed.

The most helpful way to check which type of exception is being thrown is to ITERATE THROUGH ALL INNER EXCEPTIONS. I CANNOT STRESS THIS STRONGLY ENOUGH!! 99% of the time, System.Web.Mail throws the "Could Not Access CDO.Message" exception. This message is not too helpful, however, by checking the Exception.InnerException, some additional helpful text is usually found that will shorten your troubleshooting time CONSIDERABLY.

A very good post at gives a good insight into the problem

Hope this help

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