PostcardBulkMailing.com

The United State Postal Service (USPS) defines bulk mail as large quantities of mail prepared for mailing at reduced postage. Basically, bulk mail is commercial first-class mail and advertising mail (called standard mail by USPS). The terms "Bulk" and "presorted" as the same.

Bulk mailing postcards are postcards sent at a reduced or discounted rate from "Single piece" mail. When you mail advertising at a single piece rate that is when you put a stamp onto a letter and mail it individually. Sometimes that is the easiest if just mailing a few business letters but when conducting large marketing campaigns that can be very costly.

Bulk mail postcard rates are set up to be discounted because before you mail the postcards, you do some of the work for the post office. For example, depending on the mailing permit you have, you may be required to sort all of the postcards by zip code, and or mail the postcards from a bulk mailing facility instead of the local post office.

Before you can take advantage of bulk mail prices you will need to get a Mailing Permit and pay the annual mailing fee. Buy postage for the postcards- precanceled stamps, postage meter or postal imprint.
Make a decision about the exact size, shape and weight of the postcard. presort all the postcards by zip code and then mail the postcards at the designated post office or bulk mail center.

Official Size for postcards for USPS mailing
Rectangular
At least 3-1/2 inches high x 5 inches long x 0.007 inch thick
No more than 4-1/4 inches high x 6 inches long x 0.016 inches thick

Minimum Quantities for Bulk Mail Discount Pricing
The more you mail the lower the cost for the postage seems to be. Depending on how far your postcards are being mail to. These are the general rules, but when you buy your postage meter from USPS they will give you all the exact requirements:
500 pieces first class mail
200 pieces standard mail
50 pieces for parcel select
300 pieces for presorted or carrier route bound printer matter
300 pieces for library mail
300 pieces for media mail (aka book rate)



You can calculate the prices on USPS official website and Business Price Calculator
http://dbcalc.usps.gov/