Postal : User's Guide to Commingling
What you don't know about this mail optimization tool could cost you time and money
March 2009 By Debora HaskelCommingling works because the U.S. Postal Service offers tier qualification and work-sharing discounts. Simply put, the less the USPS has to handle your mail, the bigger the discounts you earn. The benefits of commingling are not just monetary, however. Commingling also reduces cycle time and handling by the Postal Service, so mail moves faster through the system and arrives in-home both quicker and in better shape.
Your testing program benefits from commingling in two ways. First, even small test cells earn the highest level of postage discounts. Second, analysis of test panels is more accurate because these cells are processed and delivered with your control mail, eliminating delivery variables that might impact response rate.
Commingling sometimes is confused with combining and copalletizing. It’s critically important for marketers to understand the differences. Combining or copalletizing mail allows for destination entry discounts for drop shipments to Bulk Mail Centers and Sectional Center Facilities. Combining is the manual consolidation of mail trays onto single destination postal skids. Combining impacts destination entry discounts only.
Commingling Defined
Commingling goes a step further than combining—merging programs from multiple marketers into one mailstream, increasing SCF penetration and enhancing the accuracy of test panels, because they become part of the control package mailstream. In other words, commingling is the automated sorting of multiple mailstreams into a common mail tray. Commingling upgrades your tier qualification and provides destination entry discounts.
Commingling is effective because of USPS requirements to achieve five-digit discount rates. To qualify, mailers need a minimum of 150 pieces per ZIP code. Commingling improves the chance for ZIP codes to attain the 150-piece threshold. Here’s what happens in a typical mailing:
- Three-cell mailing with 150 pieces total for ZIP code 03458.
- 50 pieces in each cell for ZIP code 03458: All mail in 03458 will be charged at the three-digit sort rate.
- Commingling the three cells into the same tray: All 150 pieces qualify for the lower five-digit rate.
Commingling Savings
Understanding how commingling works and how it differs from combining is critical to understanding the potential value and savings. Here is an example of the commingling process at work on a hypothetical program:

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