REFERENCE
Description: Determines the behaviour of shared mail.
1 - Use the shared mail database for mail delivery. When using the shared mail database (MAILOBJ.NSF), messages sent to multiple users on the same server are only stored once.
2 -Server uses MAILOBJ.NSF for both delivery and transfer of messages.
Default: 2
UI equivalent: None, although you can specify this setting in the NOTES.INI Settings tab of the Configuration Settings document in the Domino Directory.