Did a brief research on this topic......called CIC in India and Canada and it is quite clear that you just cannot mail your passport outside of India. Someone else had the same situation like me and he mailed CIC delhi about the problem and heres what he got :-
Dear Sir/Madam,
This is in response to your recent email enquiry to the Immigration Section of the Canadian High Commission in New Delhi.
If the Visa Office where your application is in process has requested you to submit your passport for visa issuance, you must submit your passport to the same Visa Office. No other Visa Office can issue the visa, nor can your passport be forwarded by one Visa Office to another.
We understand that, if you are currently in India and your application is process elsewhere, you will encounter difficulty trying to send your passport out of India. Since Indian law prohibits the sending of passports in and out of the country by mail or courier, you are advised to personally travel to the country where the Visa Office is situated in order to submit your passport, or to request a trusted person to carry your passport to that country on your behalf. Before choosing the latter option, however, it is essential to check with the Visa Office to find out whether they will accept passports submitted by a representative. If yes, you must provide authorization in writing to your representative to submit your passport on your behalf. You can complete and print the “Use of a Representative” form at this link: http://www.cic.gc.ca/english/information/applic.... Please note that you may also be required to provide a mailing address in that country to which your passport can be returned after the visa is issued. We recommend that you check the Visa Office's website for complete information.
We trust that this information will be of assistance.
Immigration Section / Section de l’immigration
Canadian High Commission / Haut-Commissariat du Canada
7/8 Shantipath, Chanakyapuri
New Delhi
India / Inde