Be sure to backup your data Before proceeding.
 (Backup Instructions: Outlook 2003/2007, Outlook 2010)

1) On the left RIGHT CLICK on PERSONAL FOLDERS and click PROPERTIES

2) Click on FOLDER SIZE on the bottom left.

-Each 1000KB is 1 Megabyte. so if your Total Size is 250343KB then your outlook file size is 250 Megabytes

-Outlook usually works well up to about 500 Megabytes but can become slow and even crash when reaching larger sizes.

-If you outlook is under 300 Megabytes cleanup is probably not necessary, if its larger then continue...

3) Here you can scroll down to see how large each folder is and what's taking up most of your space. Often its the SENT ITEMS that are all there since you started using your computer and the DELETED ITEMS that have never been emptied.

4) Click CLOSE and CANCEL when done examining this area and the folder sizes

5) You can now proceed to delete what you don't need.

6) On the left, to delete a folder RIGHT CLICK on it and click DELETE

7) To erase just old emails, such as in the SENT ITEMS area, click once on SENT ITEMS

8) On the Right Side click on the top of the RECEIVED Column to sort by date

9) Scroll to the oldest email and Left click on it Once. then scroll up to the newest email you want to delete (e.g. 60 days ago) and Hold The Left Shift Key and Click on that email ONCE.

10) Press the DELETE key on the keyboard.

11) Do this for each folder that has information you want to delete

12) Now go to the DELETED ITEMS folder and do the same time (Step 7)

13) This time you will be prompted to click YES to permanently delete these emails as they Can Not be retrieved once deleted from here.

14) Going to Step 1 again you can see the new file size and how much you have reduced your Outlook file.