Once your Outlook mailboxes are in order, it's time to turn to your Outlook calendar. When you checked your folder sizes, you might have found that the calendar is one of the bigger culprits in filling up your Exchange mailbox. This is where large attachments designated for a single, long-forgotten meeting often hide. You may not have even attended the meeting, but the meeting request lives on.
The quickest way to root out these and other unnecessary calendar detritus is to change your calendar view. Select your calendar, go to View, Current View and then select By Category. Make a note of your existing view before you change it so you can switch it back when you're done. The default is Day/Week/Month.
The category view is a sortable list, but it's missing an important field: Size. To add it, go back to View, Current View and then select Customize Current View. Click the Fields button and then change the Select available fields from dropdown to All Mail fields:
Scroll down to select Size, click the Add button and then OK.
There, now you can sort by size by clicking the column header. Open your calendar items and check for any important notes and open the attachments to determine whether you should save them before deleting. When you're done, click the Start Date column header twice to put the oldest entries at the top. Delete any old appointments unless you need a record of your schedule. Also look for any birthdays, anniversaries and other annual events and make sure they are set to recur annually, so you don't have to keep adding them every year.
If your holidays for the coming year aren't already in place, go to Tools, Options and then click the Calendar Options button. Click the Add Holidays button and then select your country (along with any countries you do business with!):
There, now you should be ready to face the new year!