If this variable doesn't exist, or is set to "0", Notes IM is enabled. If it is set to anything other than 0 (i.e. IM_DISABLED=1), Notes IM is disabled. "Disabled" means Notes will behave as if no Sametime server is set in the location document's Sametime server field.
Also in Notes 6.5.1, relative to SPR # RMAA5UGU3B, an additional Notes.ini parameter IM_DISABLED was added to disable the IM components from the Notes client UI even if the current Location document's Sametimeserver field is populated. If this variable does not exist, or is set to 0, Notes IM is enabled. If it is set to anything other than 0 (i.e. IM_DISABLED=1), Notes IM is disabled. "Disabled" means Notes will behave as if no Sametime server is set in the Location document's Sametime server field.
The IM_Disabled parameter can be added to the Notes.INI using a Desktop policy by making use of the information in the following document: " The desktop policy in the Domino Directory can be designed to set notes.ini and Location parameters"