My wife and I are in transition and won't be able to use the organization address like we have for the past 4yrs, so I'm curious about the best way to receive mail. I'm leaning towards a PO Box. Does anyone know how to go about getting one and do I have to get it at the main station near Wat Phnom?

I don't know PO box, but sometimes (in general) they have size limitations.

another thing is have it sent POSTE RESTANTE. you will pick it up at the GPO with your passport. They will store it for I think minimum of 6 weeks.

The PP address is:
Your Name (as in passport)
General Post Office - POSTE RESTANTE
Ang Eng (Str 13/Cnr 102)
Phnom Penh 12206
Cambodia

SR:
Your Name
GPO - POSTE RESTANTE
Pokambor Ave
Krong Siem Reap 17259
Cambodia


you may have to pay a storage fee of 1 or 2 dollar, when picking it up. maybe its less, dont remember. in SR I mostly don't have to pay it.

but only the recipient with passport can pick it up.

Nice, thanks

Getting a PO box at the main post office is almost impossible unless a good hearted expat gives you theirs (and I still owe you beers, D) - if you ask at the appropriate desk they will chuckle to each other and say 'not have, maybe you come back next month'. This is a joke as many boxes have clearly been abandoned and staff don't seem bothered to follow up - obviously less work that way.

If you DO get a box number odd sized parcels are not a problem as long as your local phone number is included in your address (in fact, do this for ALL incoming mail) - the parcel desk will call you with the collection desk number and consignment number, also note the calling mobile number as this is used for validation. When I was collecting a parcel last week a number of Africans seemed to be having a very difficult time of it as they did not have these three numbers and staff were disinclined to assist. Collection costs about 6000r and is subject to inspection, apparently depending largely on either your ethnicity or lack/otherwise of facial hair - I had no issues.

Do NOT trust the security of the PO boxes furthest out of sight in the PP GPO as the front facing can be pulled far enough forward for small hands to forage. For critical stuff use a company.

they also call you with poste restante, when you have a phone number on the package.
if not, they don't call you.
but you may figure, when the parcel has a tracking number.

normal lettermail lands in a big box, where everyone can scroll through.

^ yup

If the contents of your package are interesting enough, they won't call either. It's up to you to go and search the incoming manifests (and good luck with that).

i got one no problem at all last year,
cost like- $23 iirc.
main GPO near wat phnom.

took 10 minutes.

of particular importance: make sure your phone number is written on the item by the sender.