KB Article #176655
MailGate SC Outlook Add-in cannot connect to MailGate server
Problem
MailGate SC Outlook Add-in installation fails on the step where MailGate End-User URL, username and password are entered. The error message is:
“Error: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.”
Resolution
The error indicates a SSL/TLS handshake issue which is most likely caused by the fact that MailGate's server certificate is not trusted. Typically this can be the case where MailGate uses its default self-signed TLS certificate. To verify if this is indeed the case - navigate to Admin UI > Administration > Certificates > Local > TLS Certificate and check certificate trust.In order to solve this, MailGate's TLS certificate needs to be imported in Windows Certificate Store of the workstation. The server certificate could be exported in two ways:
1. Under Admin UI > Administration > Certificates > Local > TLS Certificate > Export - this would export the certificate as a .PEM file
2. By clicking on the padlock icon in the browser's address bar and navigating through the View Certificates > Details and then using the Export or Copy to File buttons, depending on the particular browser version - the certificate would be exported as a .cer file
Once the file is available:
1. Open the Windows Start Menu and type mmc
2. A new dialogue box will open, then go to File > Add/Remove Snap-in, highlight Certificates and click Add
3. On the next menu select the Computer account radio button, hit Next, keep the Local Account selected and click Finish
4. Going back to the Snap-in page, click OK
5. Expand the Certificates tree
6. Right-click on Trusted Root Certification Authorities and select All tasks > Import
7. Browse for the .PEM or .cer file and hit Next, then again Next and Finish
8. A small dialogue with a message "The import was successful" should pop-up.
After these steps are completed, go back to the Outlook Add-in installation attempt a new connection - this time it should be successful.