Recently my Outlook 2010 OST grew to over 4GB of space which made Outlook slow.
One of the biggest reasons why it’s this large is SSW’s policy against auto-archiving and never permanently deleting anything. As a result my Deleted Items folder was actually 2.1 GB!
Now, I don’t actually need all of those items as they do span back about 4 years. So the goal is to only bring down the current year’s deleted items.