MAPI-functionality was removed in R6. In order to support customers better and compete with Outlook, there should be a standard API-based way for 3rd party apps to access basic Notes email funtions.
It is incredibly frustrating to install many many 3rd party apps (Olympus' DSs Player Pro is biting me at the moment) to realize it supports Outlook and Outlook Express, but not Notes.
I'd vote to restore MAPI on the Windows platform, but I don't actually care, as long as it works. OpenVIM anyone?
09/17/2008 UPDATE: I just added this screenshot from the Quickr Connector (v8.1). Notice anything?