General FAQs

What is Mail.dat?
Mail.dat is the industry standard for presort data.
Mail.dat files contain detailed information about a presorted mailing. This industry-standard file set is accepted by the United States Postal Service® (USPS®). Mail.dat is created during the presort process, either by presorting software processing name-and-address lists or by co-mingling equipment sorting already-assembled mailing pieces. No matter how the sortation is performed, the details that make up the mailing are recorded in the Mail.dat file set for that job.

Are the actual names and addresses stored in the Mail.dat files?
No.
The only information not included in a Mail.dat file set are the names and addresses
of the intended recipients, so confidentiality is assured.

What is Mail.dat used for?
Mail.dat provides the most accurate basis of postal documentation and more.
The information in the Mail.dat files is extremely useful in postal document preparation, mail verification and acceptance, electronic data storage, reporting, and transportation planning. The data can be used, for example, to create all of the documentation required by the Postal Service™ for the mailing, including: postage statements, PS-8125 drop-shipping forms, Qualification Reports, Manifest Mailing System Reports, bag and tray tags, as well as pallet placards. Mail.dat facilitates electronic verification and acceptance of the mail, as well as the electronic archival and retrieval of past mailing statements and data. Mail.dat feeds sophisticated reporting to the USPS, letter-shop clients, and internal departments. Mail.dat also enables more efficient transportation planning.

Why not just use the postal documents generated by the presort?
Mailers use the Mail.dat files generated by the presort as the basis for postal documentation, rather than the documentation generated by presort software or equipment, for many reasons:

1. To save on printing and shipping costs and avoid delays.
   Mailers can reduce costs and avoid delays releasing the mail when the presort is performed at a different location than the mail preparation. A service bureau or mail owner may be running the presort software, while a letter-shop or printing company may be preparing and releasing the mail. Instead of printing out all of the hard-copy documentation and shipping it to the mailing facility, the Mail.dat files can be shared electronically, and the documentation can then be printed at the remote site.
2. To speed acceptance and improve quality control when changes occur.
   Generating postal documentation from Mail.dat data becomes even more useful when modifications such as changes in piece weights, ad percentages and piece counts to a mailing job are required. Changes can be made to the Mail.dat files without re-running the presort. These changes can then be easily and accurately reflected in the postal documentation without having to perform manual computations.

   For example, in order to use presort software, the weight of the mailing piece must often times be estimated; however, the actual weight of the finished piece may then differ from the estimate. By editing the piece weight in the Mail.dat file before producing the documentation, the accurate weight is captured. Also, in Periodical mailings, the advertising percentage often requires similar, last-minute changes that can alter the final postage calculations. These changed ad percentages may be easily accommodated by editing the Mail.dat files prior to generating postal documentation.

   One last example is an unforeseen event on the production floor, such as piece-spoilage or running out of forms, after the presort plan has been completed. In these cases, piece counts may be altered in the Mail.dat file, in accordance with USPS rules and regulations, to accurately account for the changes.

   All of these examples clearly show how using Mail.dat can improve your mail quality control and speed acceptance of the mail.

3. To speed delivery and/or save money via drop-shipping.
   Another common change that is made after presort is the choice of entry point locations to take the mail to. The trays, sacks and/or pallets in a mailing job can be “drop-shipped” to various postal facilities in order to speed delivery and receive additional postal discounts. Mail.dat files contain all of the information necessary to determine which postal facilities the mail is eligible to “drop” at.
   From the various eligible entry points, mailers can choose which ones are preferable for their specific circumstances. The decision may involve a desire to speed delivery, to save postage costs or a combination of these factors. The entry points can be edited in the Mail.dat files so that the postal documentation reflects these changes, without re-presorting the name-and-address files.
   Larger, more sophisticated mailers may even use the Mail.dat data to optimize the entry point selections automatically by comparing shipping costs to postage savings and selecting only locations where the savings outweigh the cost of shipping.
4. To benefit from the flexibility to split and merge mailings.
   Mailers often find it necessary to work with only part of a mailing or with multiple mailings simultaneously. For example, a presorted mailing job may include more than a million pieces, but the printing facility may only be capable of producing 300,000 pieces per day, requiring that the job be released over several days. Postage statements and other documentation may be needed for the mail released on each day, but the presort software generates this information only for the entire job. Using the Mail.dat files, the mail preparer can select only that portion that has actually been produced on any given day and produce the required forms.

   The Mail.dat files can also be useful when almost the opposite situation occurs. Sometimes, multiple presort jobs are required for a single mailing because multiple versions must be produced in separate production runs. If these are released on the same day using the same permit information it may be beneficial to create consolidated documentation. Consolidating multiple jobs may even involve co-palletization, where trays or sacks from multiple jobs are combined onto common pallets. This further increases the opportunity for drop-shipping eligibility, which can mean additional cost savings for you and your customers.

5. To save space and money by reducing paper documentation and storage
   The Qualification Reports can be presented to the Postal Service electronically, instead of in hard-copy form because Mail.dat is recognized by the USPS as an approved format for the electronic submission of mailing information via the USPS PostalOne!® program. The PostalOne!® program also includes electronic postage payment for some classes of mail. As the USPS moves ahead with the PostalOne! program, all mail types will be available for electronic payment. This eliminates the need for printed postage statements. PostalOne! also expects to facilitate electronic mail tracking and drop-ship appointment scheduling.

Can First-Class mailers benefit from using Mail.dat?
First-Class mailers enjoy reduced paperwork and labor through Mail.dat use.
Mail.dat provides a principal way to access the USPS PostalOne! program. While many recognize that Mail.dat offers significant benefits to those people mailing Standard Mail™—particularly drop-ship discounts and the ability to communicate electronically with supply chain partners—the Mail.dat file set also presents those mailing First-Class Mail™ an opportunity to exchange mailing information electronically with the Postal Service. First-Class mailers—both manifest and commingled-presort mailers—can leverage the same advantages for e-documentation and e-payment that exist for Standard and Periodical mailers. (See below for a Summary of Mail.dat Benefits by Class of Mail.)

Several major telecom and utility companies have been using Mail.dat to drive manifest systems to document their First-Class mailings. At least two providers of Multi Line Optical Character Reader (MLOCR) presort machines have demonstrated the ability to create Mail.dat files that could be used to drive a number of applications.

The Mail.dat format is widely available for First-Class mailers in both the manifest and multi-line presort environments. Discuss these options with your software and presort vendors. The benefits of reduced paperwork and labor for electronic documentation and payment, along with the ability to know where your mail truly is in the mail stream, offer substantial value-added services for your customers.

Summary of Mail.dat Benefits by Class of Mail.