ThanksYou may want to contact them, because if you are in Singapore, I remember seeing somewhere else on the forums that people were sending their PPs to Singapore VO or processing center.
I am in US and I have the Laurier Avenue address in the CPC email. I never received a message on CIC profile so can't comment on that. If your wife is in Canada then probably she will have to send it to the PO box. However once again I would advise you to contact CIC and confirm or generate a Case Specific Inquiry.