Sorry, that's only part of it. I C&P the bit that seems to suggest you can send it to ADVO from overseas. Mine also said:
If you and all the accompanying dependents on your application are currently in
Canada and plan to be in Canada for at least three months, you may submit your
passport(s) and other required documents to the Case Processing Centre – Ottawa
(“CPC-O”). You are required to send your passport(s) together along with a copy of
this letter by mail or courier to the following address:
If sent by regular mail or Canada Post Xpresspost (recommended option)
CPC – Ottawa
PO Box 9780
Ottawa, ON, K1G 4B9
Purchase two prepaid letter-sized (32 x 24 cm) Canada Post Xpresspost
envelopes (Regional if you live in Ontario or Quebec; National for other
provinces and territories), at any Canada Post retail outlet.
Complete the mailing label showing your full mailing address in the “Deliver
To” field.
Make a note of tracking numbers for each envelope.
Enclose both envelopes along with your passport and a copy of this letter.
You can purchase a Canada Post shipping label on line:
http://www.canadapost.ca/personal/tools/cst/intro-e.asp
If sent by private courier (only)
CPC – Ottawa
365 Laurier Avenue West
Ottawa, ON, K1A 1L1
If you choose to not provide us with a return Xpresspost envelope, we will
return your passport(s) via regular mail (Canada Post Lettermail). Passport(s)
will not be returned by private courier. Do not provide any pre-paid courier
envelopes: These will not be used.
The whole document attached to the email is 8 pages long which is why I didn't C&P the whole thing.