The marketing diary can be accessed by clicking Admin from the Main Menu and then by selecting Marketing. You are then given a list of choices with two of them relating to the diary.
Diary today shows diary items that are due today for everyone or by individual staff.
The Diary all shows all outstanding diary entries irrespective of when they are due. Again this can be for everyone or individual staff.
This is not the same as the Diary that can be viewed in the Clients module and is totally separate. It will only show events which have been set up as part of a Mailshot, where an Action By date has been recorded.