VERIFIED SOLUTION i

Changing the Mail.dat version generated by MailStream Plus

Product Affected: MailStream Plus™
Product Feature: Mail.dat / PostalOne!
Operating System:  All Platforms
 
The MailStream Plus™ (MSP) software parameter that changes the Mail.dat version can be found in the REPORT MAILDAT parameter position 72. The MSP application by default will use [C] the current Mail.dat version but the software offers the option to use the [P] previous Mail.dat version. 

The Release Notes for the MSP version being used tell what version is produced by the C or P options.
Also, the Mail.dat HDR file in Field Code HDR-1101 (positions 9-12) indicates the Idealliance Mail.dat version.
 
UPDATED:  March 12, 2019