Tool Tip warning user when a folder contains too many items and causes performance degradation
We have been advised by our Premier Support engineers and the Product Group that folders, specifically the calendar, should not have more than 5'000 items. When there are more than 5'000 items, the user will experience significant Outlook performance issues. The user has no way of knowing, today, that this is a problem or that a folder with more than 5'000 items will cause Outlook performance issues. For many users, a mailbox's size is virtually unlimited and there is no real thought to managing the number of items in any particular folder. The two principle problem folders are Calendar and InBox.
Microsoft does provide controls and tips for some limits but not for folder items. For example, users cannot send mail when their mailbox is full, they get a Tool Tip if their mail exceeds the maximum size set by an administrator, and gets a Tool Tip if there are too many recipients for a mail. There is no such tip to advise users when they have situations known to cause performance issues which result in a bad user experience.
Create a Tool Tip that warns the user when a folder has more than 5'000 items and offer advice to the user to ensure a good experience, e.g. archive items, delete items, move items, etc.