Instructions when receiving a passport request.
Once your Canadian visa application is approved, you will receive a letter requesting you to send your passport to collect your visa. You can send your passport anywhere you legally reside, if there is an office that accepts it.
If you are in Vietnam :
Please bring the following documents:
- Your original passport must have at least one blank page and be valid for the duration of your studies in Canada.
- The "Passport Request" letter, within 30 days of receiving this letter.
Note: The unique client identification (UCI) number in this letter is important for life and must be kept confidential. Do not give this number to anyone except for presentation to relevant authorities.
The place to submit your passport application in Vietnam is the VFS office: https://visa.vfsglobal.com/vnm/vi/can
If you are in Canada:
If you are applying for a temporary visa, student visa, or tourist visa within Canada, you will need:
- Post your passport to the receiving location in Canada.
- Passport cannot be submitted in person.
You can expect to receive your passport back after 14 business days . However, this timeframe may vary depending on the postal service provider.
You should use Xpresspost or Priority Post postal services.
1. Buy two Xpresspost envelopes as shown in the picture, one large (for sending), and one small (for receiving your passport): 
2. If you are in Ontario or Quebec, choose envelope. grid
If you are in a different province, choose the national envelope. 
3. Take photos of the tracking numbers (barcodes) on both envelopes to keep, so you know where your mail is and when you can receive it back.
4. In the small envelope , write your full name and address accurately in the "To" section (your passport will be returned to you).
Note: Please write your name exactly as it appears on your ID (driver's license, student card, etc.), not a nickname. Include your phone number so the recipient can contact you if the card is lost. 
5. Put it in a large envelope:
- Your passport must be valid for at least 12 months and have enough pages for visa stamps.
- Print the letter requesting passport submission.
- small envelope
Send a large envelope to:
BIG:
Temporary Resident Visa Section
CPC-Ottawa (e-Application)
PO Box 9640
Ottawa, Ontario
K1G 6T2
http://www.cic.gc.ca/pp-md/pp-list.aspx