VERIFIED SOLUTION i

MailStream Plus- is there a Maximum weight for sacks(bags)/trays using the BG MAX parameter?

Product Affected:  MailStream Plus™ - all versions, all platforms
By default, MailStream Plus (MSP) will use the USPS's maximum weight of 70 lbs for trays/sacks.
A 'BG MAX' parameter can be used to increase the maximum weight up to 99999 using parameter positions 28-32.  In fact, you can extend that 1 position to the left, and have the value 999999 in positions 27-32.

FYI- If you have increased the weight and still see the presort results making sacks/trays with less weight than you set on the BG MAX, then consider that sacks may be maxing out on the volume that will fit into a sack, or trays may be maxing out on the thickness of mail that will go into a tray.
Maximum volume and thickness can both be set up on the BG MAX parameter as well. 

Note: By default, MSP uses the USPS's limit for maximum weight.  The MSP default maximum volume for sacks was determined based on the size of the sacks, and the default maximum thickness in trays was based on the USPS's tray sizes.  So only increase them if you are sure the presort results will still be acceptable.

Per the Domestic Mail Manual (DMM) as of Dec 2018, here are the references:
Trays 203 5.6.2c The weight of a tray and its content must not exceed 70 pounds
Sacks 203 6.2b The weight of a sack and its content must not exceed 70 pounds.

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UPDATED:  December 27, 2018