After migrated to Exchange, I cannot receive scanned document with more than 4 pages?

It is known that the default maximum email size of the Send Settings with some scanners (e.g. Ricoh MP6000) is 2048 KB. Scanned documents larger than the max. email size will be spited into trunks before sending to user's email account. In this case, the sender will got the following error:

fatal errors (reason: 554 5.6.1 Messages of type message/partial are not supported)

Turning off the maximum email size of the "Send Settings" should fix the problem. Please refer to the printer's manual on how to disable the setting or seek help from the vendor's support hotline.