We have a really great piece of data recovery software called E-Recovery For Outlook Express, that will restore deleted emails. The software is very easy to use, you just select the email folder the emails were deleted from and then we show you what we see for recovery.
Now the reason I am bringing up this data recovery software is because I had a few customers call and tell me they could not find emails more then a few days old or a month old. So in order to set the background, you have to understand that each one of those folders is a mini database file on your hard drive. As you send and receive emails those folders grow.
Eventually, you will open Outlook Express one day and it will ask you if you want to compress older data. Windows makes this all sound very appealing, like it is going to make everything work better. The truth is that yes the files will be smaller and maybe Outlook Express with run a little faster, but in the event one of the DBX files gets corrupt, data recovery will be next to impossible because the compression is different from DBX to DBX based on the data being compressed. For this same reason E-Recovery can only see emails that have not been compressed.