In the Notes client -> File menu -> Preferences option ->User Preferences -> Instant Messaging tab -> Options, you should check the box “Save my discussion in my mailbox” (something like that, sorry my software is in French … lol)
For server based IM journaling or logging, you should use a 3rd party product. Server based IM journaling/logging
is available and can be enabled via these instructions:
More robust chat logging capabilities is available with a 3rd party product. Here’s just one company that does this.
This offers chat logging and auditing.