Mail.XML vs. Mail.dat

Mail.XML vs. Mail.dat

Most of us in the mailing industry have become accustomed to the word "Mail.dat" and have a good understanding of what it is and the benefits of using it. For those of you still not familiar with the term Mail.dat, it is a mailing industry standard specification (established and maintained by IDEAlliance) for a set of relational database files. These files are generated at the time when the mailing list is sorted through postal presort software, or when the mailpieces are sorted on MLOCR. The set of files together represent just about all the specifics about a mailing with the exception of the mailing names and addresses. These files are used by the mailing industry and the United States Postal Service® to share information and facilitate electronic transactions.

Just when we thought we had become pretty smart about Mail.dat, along comes Mail.XML. Unless you are a real techie, Mail.XML probably seems like a word from foreign language. Actually, Mail.XML is fairly simple, and it represents a really cool method to transmit mailing information. But what does it mean for the average mailer? As background, Mail.XML is a newer mailing industry standard specification (again established and maintained by IDEAlliance) for informational transmissions. Mail.dat is quite robust and can contain huge amounts of information. This is very beneficial, except when you only need portions of the information that resides in Mail.dat files. In these cases, it can be time consuming and a strain on transmission and storage resources to send entire Mail.dat files back and forth between the involved participants in the mailings.

To help understand the difference between Mail.dat and Mail.XML, think of it in terms of the Mail.dat file being the encyclopedia of a given mailing. Then think of Mail.XML being the telegram that you send to someone describing a portion of the encyclopedia. If your recipient only needs a small segment of information, it is much easier (for both of you!) to send them a short telegram than to send them an entire encyclopedia. That is essentially how Mail.XML works in relationship to Mail.dat. One of the ways that Mail.XML will be used is during transactions with the USPS. For example, if you use PostalOne! to transact business with the USPS, you will first upload a Mail.dat file for the mailing as a "planned" mailing. Once all the final attributes of the mailing have been determined and all adjustments made to the Mail.dat file, you need transmit only Mail.XML "telegrams" to the USPS to update the Mail.dat file that you previously uploaded. This eliminates the need to re-upload an entire Mail.dat file every time a change is made or a new transaction required. This allows you to pay postage, make drop ship appointments, and a variety of other transactions using much smaller chunks of data.

Mail.dat is not going away anytime soon, and will certainly not be replaced by Mail.XML. Mail.XML is just a very useful tool for use in transmitting smaller chunks of a Mail.dat file. You will be hearing lots more about Mail.XML, particularly as the USPS proceeds with the integration of Intelligent Mail®.


Just when we thought we had become pretty smart about Mail.dat, along comes Mail.XML. Read and find out more. Visit