assign data based on data in another cell

I have a situation where I need to merge data for mailing lists. I've been doing it manually in Excel with no problem, except we're about to be doing a lot more lists, which means I need to automate.

Each zip code in the areas we mail is assigned to a mailing zone which coordinates with the mailed piece delivered to a resident. Example: Anyone that lives in 90210 would be in zone 1 and would receive a printed mail piece specifically for zone 1. Anyone living in 08008 would be in zone 2; they would receive the mailer specifically for zone 2 and so on. So when I get a mailing list of 12,000 residents, I need something to identify all names with say, 90210 as the zip code, and assign it to zone 1. Eventually, I'll need it to handle every zip code in the US, and who knows, maybe 2500 zones.

I was thinking of creating a database for just zip codes and zones. Kind of a master file, so there is a point of reference coordinating zones and zip codes. Then when I get a list of names to mail, I need something to reference the recipient's zip code, and in a new column assign the proper mail zone. Then I want to export that list and send it off to the printer.

Any ideas how I can make this happen via Excel and/or Access? Is there a trick I'm missing where if someone's zip code is in say, column G, and Column H was blank, that a code in Column H would reference the zone database, and know that if it found 90210 in G1, that it would automatically populate "zone 1" in H1? Kind of like an IF function, but with a few thousand layers.

Set up one sheet that has the zip code in column A, and the zone in column B.
Then on your column H, you can use a vlookup to fill in the zone.