Aug 24, 2011

Problem with the proxy server’s security certificate (Error code 0)


When using Outlook 2007 connecting to our Exchange server through the public URL, I get the following error: There is a problem with the proxy server’s security certicate. The name on the security certificate is invalid or does not match the name of the target site

Outlook is unable to connect to the proxy server. (Error Code 0)

(The message has our company URL instead of Contosco) We’ve set this up with self-signed cert and the system works remotely for all of our remote computers except this one. This one is different in that it is the first Vista 64bit to be tested for deployment. It’s Vista SP2 also. Our mail server is set up FQN of mail.contosco.local.

I’ve made sure if I visit the website using a browser, that the certificate is considered trusted since I have installed the signing cert into cert list.

If I turn off the “Only connect to proxy servers that have this principal name in their certificate:” which contains msstd:, then it works. I’m convinced all the other settings are the same as our other Vista Outlook 2007 machines which all work. Any ideas?


This error can arise when there’s a mismatch between the common name of the certificate and the “only connect to proxy servers” setting. Check out this article for more information on troubleshooting.

Related posts:

  1. Outlook Trust Certificate SBS 2003
  2. Cannot open encrypted email in Outlook 2007. Error: “Cannot open this item. Your Digital ID name cannot be found by the underlying security system.”
  3. Exchange Server 2010 ActiveSync SSL Certificate Problem
  4. same SSL certificate in two servers
  5. How to configure Apache to reject proxy requests with error code?

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