If you read your email carefully, it should say something like:
Step 2: Determine if you need to submit passport.
If you are a holder of passport from countries whose citizens need visa to travel to Canada. Then you will need to submit passport for you and all accompanying family member. Your passport must be valid for at least 6 months and with 2 blank pages.
Please note that you will still have to submit passport if:
1. You have a valid Canadian temporary status visa (workpermit,studypermit or visitor visa)
2. You are USA permanent residence holder and holder of passport from countries that requires visa to travel to Canada.
If you are a holder of passport from countries whose citizens are exempt from obtaining a visa to travel to Canada, then you will need to submit one photocopy of passport page.
So in conclusion, if you are from a country that needs visa to travel to Canada, you will have to submit passport for PR visa stamping even if you are on work permit. The address to mail to should have been in the PPR email.