Prior to Cognos 11 when you scheduled a report you had the ability to change the subject of the email and also the recipients. It appears those options are no longer presented using the Subscriptions method. As an Admin I can still get to the Admin Console and modify schedules to change those settings, but how do I have end users do that?
Subscriptions are a vastly simplified form of scheduling in Cognos Analytics, and really just for self-consumption. The original, full scheduling capabilities are still there too for users. You find a report in the portal, click the inverted ellipsis (three dots) next to the report name, choose "Properties", then go to the Schedule tab. Click the + to create a new schedule, and in the Delivery options, choose "Send this report by email". The user then sees the options for To / Subject / cc / bcc etc, and can enter whatever they like.