It is possible for the system to use the date entered in the mail received box as the posted date for incoming mail. This is setup in the System Parameters program by following the steps below:
Ensure the Override history dates setting is ticked in the Default User Profile.
Enter the System Parameter Maintenance Program.
Check if the 'Use Date Received For Post Date' system parameter is currently active. If it is, this parameter will take priority so you will need to click Update, change the Value to No and click Save.
Click on New.
Within the Key field type Email and Incoming Files.
Within the Code field type Set Posted Date as Mailed Received Date.
Within the Value field type Yes.
Click on Save.
Exit the program.