Makesure you are in the Department.
Download the certificates of our Server CA from the link http://www.cse.iitk.ac.in/users/ca/certificate.crt.
Start thunderbird and click on Edit -> Preferences -> Privacy -> View certificates -> Authorities. For thunderbird 2 it is Edit -> Preferences -> Advanced -> View certificates -> Authorities. You will see a list of CA's including popular names like Verisign, Entrust etc. The exact menus might be slightly different depending on versions and the fancies of your packager but it is more or less along this lines
Click on Import and select the files downloaded in step 1. Verify the finger prints of the CA's.
If everything goes on fine you will see the listing of our Server CA Certificates in the list of Authorities in step 2.
Now you are ready to use your IMAP server. The annoying "Cannot trust this site" dialog wont occur now.
Last modified on 08 April, 2010 (Thursday)