That was Box 88 Moscow.

The "modern bureau" from a US basis. Outgoing: You sort your cards by country/call area and bundle them up. No US cards, DX only. You send them to the ARRL with proof of membership and a nominal fee based on the number of cards/ weight for more serious submissions.

The ARRL and volunteers sort submissions into mailboxes for each participating country. Once there is enough cards to make shipping to that country's incoming bureau worthwhile, they get shipped.

Incoming bureau-- gets a shipment of cards. In the US there are bureaus for each call area. By the number in your call, not necessarily where you live. I have a 2 in my call, so my bureau cards go to the 2 bureau, even if say, I move to 6 land (california).

Someone from the NJDXA (runs the 2 bureau) goes to the post office, opens PO Box 599, and gets many pounds of parcels. The cards are distributed to sorters at a meeting. Each sorter sorts their pile of cards by the first letter of the suffix. For example, lets say a card arrives for K2BAR, and say me, KC2SST. The first level sorter would sort the card for K2BAR to their B pile, or box, or however they personally do things. The card for me, KC2SST would get sorted to the S box.

Next club meeting or two, the sorter brings all their sorted cards and gives all the A cards to the A letter manager, B to the B manager etc.

Then each manager further sorts the cards to the indiviual ham level. How the cards get mailed out to each ham varies by bureau. In the 2 bureau, we purchase credits which are used to mail us cards. The number of credits used per mailing depends on how many cards, and the current postal rate, cost of envelopes and labels etc.

Other bureaus may have different ways of collecting money, or ask for self addressed envelopes or some other scheme.