In your case, CP will likely leave a missed delivery note in your mailbox which you can collect the same or the next day by visiting CP. At the same time, I have read more than couple of cases across this forum that CP has literally crammed the certificate inside the boxes by folding the envelope - much to applicants dismay lol. Although it shouldn't matter tbh. Also there was atleast 1 instance where Purolator
was used for Certificate delivery - which really concerned me because I had terrible experiences with government issued docs couriered with them. They only handover deliveries by hand and if they don't have access to the intercom (which is the case in my building), you will need to wait for a day (sometimes 1+ week in my case) and travel far to their sparsely located branch to collect. Fortunately for me, like the OP, I have the bigger shared CP mail box in my building as well. In any case, I have yet to be scheduled for Oath, so yeah thats the least of my worries now LOL.