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How to control getting Outbound and/or Inbound records in the Mail Piece File with MailStream Plus or Mail360 Manager.

MailStream Plus and Mail360 Manager™, all versions, all platforms
The Mail Piece file is a file that can be produced using the IMBCTL parameter in MailStream Plus™ (MSP) or in Mail360 Manager.  The primary purpose of the file is to be input into a separate product 'EngageOne™ Inform (formerly 'EngageOne Delivery Audit', and before that Mail360 Data Manager') for Mail Piece tracking through the USPS delivery process.

In MSP and in Mail360 Manager, the settings allowed on the IMBCTL parameter position 8 are:
B   Assign both outbound and inbound Intelligent Mail® barcode numbers. This value is valid for Intelligent Mail® barcodes only.
I    Assign only inbound Intelligent Mail® barcode numbers. This value is valid for Intelligent Mail® barcodes only. 
O   Assign only outbound Intelligent Mail® barcode/Intelligent Mail® Package barcode numbers.
U   Assign outbound and inbound Intelligent Mail® barcode numbers based on the value in the input file. This value is valid for Intelligent Mail® 

In Mail360 Manager, you can also produce the records via a callable routine, and the field that controls which records you get is 'mpsetType':
Field                Description                         Data Type      Max.
                                                                        Length
mpsetType            Specify the mailpiece set type.       char          1 
                     O Outbound Mailpiece Set
                     I Inbound Mailpiece Set
                     M Outbound with Remittances Mailpiece Set

                     
'M' means both an outbound and an inbound record.  ('Remittance' is often used interchangably with 'inbound', because inbound mail pieces often are payments from a customer to a business.)
UPDATED:  July 22, 2019