What is Mail.dat?

Mail.dat is not a software system. Mail.dat is a data format standard for communicating data describing the composition of a mailing. This data can be used for:

• logistics planning
• labels and reports for mail production
• postal payment and acceptance
• making drop ship appointments

The Mail.dat format specification, administered by the International Digital Enterprise Alliance (IDEAlliance), has been adopted industry-wide, making it possible to send and receive data describing mailings without the need to translate proprietary formatting specifications.

What Does It Look Like?

The Mail.dat standard defines detailed record formats for a set of files which, taken together, are capable of representing virtually "everything one needs to know" about a specific mailing, including data at the segment (presort), container (pallet), handling unit (sack or tray), and package levels. (Individual address-level information is not included.)

The current Mail.dat standard (version 11-1) comprises 21 files (some mandatory, some optional). These record formats are updated from time to time as the Mail.dat Workgroup identifies changing needs.

Key fields in each of the files act as links to related fields in the other Mail.dat files. With such linkage, the complete Mail.dat file-set serves as a fixed-format representation of a relational database.

But not any specific database.

The Mail.dat files are all ASCII fixed-format ("flat") files, making them a perfect medium for communicating the complete set of data describing a complex mailing, as passed from one mail services agent to another. These files can easily be imported into any relational database management system or can be used as-is by in-house software.

For detailed information about the current Mail.dat format specifications, contact the IDEAlliance.

Mail.dat and PostalOne!

The United States Postal Service (USPS) has adopted the Mail.dat format for use in its PostalOne! program. PostalOne! allows mailers to submit data electronically – in Mail.dat format – to the USPS for postal acceptance and payment purposes. Submitting documentation and paying postage electronically through PostalOne! are two of the requirements for qualifying for Full Service IMb discounts and benefits.

Receiving and analyzing this information electronically, in lieu of hard-copy format, speeds mail acceptance processing time while reducing costs. The PostalOne! program also reduces bottlenecks in mail handling facilities by providing more information related to logistical requirements, therefore improving the efficiency of mail delivery nationwide.