User has to know which list emails he is not receiving. Then the users can check their subscription status from the URL" http://lists.iitk.ac.in/mailman/listinfo/".
Then after going to "Edit Options", check "Disable mail delivery: section, it should be off. Else reset you password from their and toggle that options.
Do not use a valuable password while setting/resetting password in list server.
To enable Digest mode, Above "Edit Options" can be used.