Certificates in a sealed envelope means that the university should pack your degree/mark sheets in an envelope and seal (close it with their stamp).
This should be un-opened by anyone other than the final authority. In case of RFE, the final authority would be USCIS.
To request the sealed certificate, most of the universities in India have now set up online as well as a physical desk in their public dealing office. You have to check your specific university’s website to see if they have any such facility online.
1. Delhi University, Delhi
Designated desk (window) at their North Campus. It usually takes 10 days for them to process the request.
2. IP university, Delhi
Designated window at their main campus in Dwarka, Delhi to process your request. Takes about a week to get the transcripts.
It is not mandatory to be present in person. This again, depends largely on individual university rules.
Your representative like parent or friend with a valid proof of relation or a written authority from you can request for it on your behalf.
Most of the universities will charge a fee for it. The fees is charged per envelope that you request.
We would recommend that you procure multiple copies of sealed envelopes as you might need them for other Visa/ country travels.
For example, Canada and Australia require sealed envelope certificates for verifying your educational qualifications.
The time to get the sealed envelope would vary by individual university. You should plan for at least 2 weeks time frame.