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Private mailbox (PMB)

published · September 10, 2026 · updated · September 22, 2026

A private mailbox (PMB) is a box rented at a commercial mail receiving agency (CMRA), written as a PMB or # number after that agency's own street address.

A private mailbox — a PMB — is a box rented at a commercial mail receiving agency (CMRA) rather than from the postal service, written as a PMB or # number after that agency's own street address. On paper it looks like a suite in an office building, because that is the form the postal service requires.

What Spaw answers

is_private_mailbox is the flag and address_type reads private_mailbox. At +60 it is the heaviest of the four delivery-point weights, though not the heaviest weight in the address product: an address the deliverability check reports undeliverable carries +80.

The detection is the interesting part: it comes from the way the postal service requires such an address to be written, not from a licensed database of agencies. A PMB 214 after a street address is the tell, and it is a rule about spelling rather than a lookup. The postal service also accepts # 214, but flats and suites are written with a # too, so a bare # number is read as a unit and never as a private mailbox. South Africa's PostNet Suite numbers are the same arrangement and are read the same way.

The limit that follows from that

A private mailbox written without its PMB number, or with a # in its place, is indistinguishable from a suite. Where the licensed deliverability check would answer the question outright, this service does not run it — is_cmra stays null and the postal service's own CMRA record is not checked — so the flag catches the addresses that are written correctly and misses the ones that are not.

A PMB is not a lie. It is a mailing address, useful and legal, that says nothing about where anybody lives.

Related

markdown version: /glossary/private-mailbox.md

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