I have a .pst file that was over 1gig in size. I started to notice a decrease in performance so I started deleting some older messages that I was holding on to. After deleting quite a bit of information and getting no results I started a search for a program that could help optimize Outlooks performance. I stumbled across this product and installed it immediately. PSTCompress found my .pst file and two other ones I was not aware I even had. I set it up to compress the .pst file, zip my attachments, and empty my deleted items folder. Lastly, I processed my problem 1027402 kb .pst file. After nearly a three hour wait I was shocked to see a 72 percent compression of my .pst file! I recommend this product to anyone looking for a product to reduce their pst file without loosing any critical data. Outlook is now performing twice as fast with no hiccup’s. Cons: This thing takes a while. I wish they could give me some sort of analysis on how long it will take to run before and during the compression process. Besides that PSTCompress does exactly what they say it does. Great product!