Passport return after initial citizenship application

INIS are getting back to me on this but thought I might get an answer faster here. My passports were posted back to me by Express Post in August and tracked as delivered but I haven't received them. I now need to take this up with An Post so could anybody tell me what type, size and colour of envelope their passports were returned in, and whether it had anything written on it/any other distinguishing features? There were two passports in case that might make a difference. Thanks very much.

Mine came in 2 envelopes, one was a plastic one of color white and inside it was a yellow envelope with my info written in it.

My two passports were sent back in a white plastic envelope (Size C6). This was 2 years ago.
INIS bulk-buy prepaid AnPost stickers and stick one of those on the envelope.

AnPost normally just puts the envelope directly into your letter box, as the envelope will say that no signature is required. There is a chance that they put the passport in the wrong letter box.

My passports were sent back last month in a white plastic envelope, I believe the size to be a A6. Inside was a regular yellow envelope with my address writen on it. I think a signature is normally required as the postman rang the doorbell and veryfied my details. On the other hand though, during the pandemic there is no signature requirement as far as I know, so they can just leave it in your postbox in case nobody is at home.

Four passports, all received in one big envelope. I found them in my letterbox in the morning.
I recommend you to contact them and ask if they were actually posted to the correct address.

Thanks everyone. They are investigating and contacting me, and An Post are apparently doing the same.

Hello!

Just adding to this thread on a somewhat related note.
I've submitted my application and am waiting for my passport now.
In the timeline threads, I'm seeing people receiving acknowledgement dates.

How are they acknowledging receiving the application? Is this via email, post or a phone call? And is this tied explicitly to receiving your passport back?

agliolio - the Acknowledgement is a letter received by post which also contains the payment receipt and your passports.

Regarding my missing ones - they randomly turned up yesterday, over a month after they were supposedly delivered! Thanks everyone for your advice.