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CSA (Customer Supplier Agreement)  
The Customer/Supplier Agreement (CSA) is a module within the FAST application. A CSA is written notice that confirms, for a commercial mailer, the origin-entry preparation requirements and the acceptance window times necessary for mail to be considered entered into the postal network on “Start-the-clock Day Zero” (Day-0). A CSA may also include a schedule of transportation times, mail containerization specifications, designated postal mail facility entry locations, and time-sensitive mail entry instructions.

“Start-the-clock” is the date and time when a mailpiece enters the mailstream. “Start-the-clock” Day Zero is the date when the clock starts for purposes of service performance measurement. A CSA does not create a Postal Service™ guarantee, promise, or commitment to process and/or deliver within the applicable service standard, or within any in-home target date or window.


synchronize the acceptance of business mailings with mail processing operating plan,
align the Postal Service’s processing and network capacity with workload demand,
reduce the randomness of volume arrival,
allow the Postal Service to optimize mail flow through its processing plants,
inform mailers of service expectations based on the time of origin entry,
can describe separation and containerization standards requested of the mailer that are not covered in the optional containerization requirements described in the Domestic Mail Manual (DMM®) (in these cases, CSA preparation requirements would take precedence when applicable), and
can benefit some mailers by allowing additional time to prepare mailings to finer sortation levels.

CSAs will be established for mailers:

who have their origin entered mail verified at a Detached Mail Unit (DMU),
who perform additional mail preparation in order to enter mail after a Business Mail Entry Unit’s (BMEU) normal critical acceptance time, and/or
whose volume warrants multiple dispatches to the BMEU to avoid the entire mailing being presented close to or at the units CAT
Mailers meet with a variety of postal personnel including (but not limited to) the Manager, Business Mail Entry, District Manager, and Plant Manager, to discuss the mailer’s operational capabilities, volumes, as well as preparation requirements. The Manager, Business Mail Entry, will then work with each mailer to create the CSA. For First-Class Mail, the MBME will indicate in the CSA the container labeling instructions, mailer requirements for separations and containerization. For all mail classes, the CSA will define the dispatch/arrival time(s), transportation, DMU requirements (if applicable), and mail acceptance requirements.

Upon sign-off on a hard-copy version, the CSA will be entered into the FAST (Facility Access and Shipment Tracking) application. At that time, the mailer will be provided a Customer Registration ID (CRID), if the mailer doesn’t already have one, as part of the CSA information. The CRID is an identifier the USPS uses to identify a customer at a specific location.

To obtain access to CSA apply for Customer Supplier Agreement through the Business Customer Gateway.