You can export your email to a pst file, then after reinstalling Outlook, you can import everything back in.

Exporting:
1. Open Outlook
2. Click File
3. Click Import/Export
4. Export to a file > Personal Folder File > highlight the top folder and check the include subfolders box >
5. Browse to the location that you would like to save the PST file (i.e. your desktop)
6. Click Finish

Importing:
1. Open Outlook
2. Click File
3. Click Import/Export
4. Import from another program or file
5. Personal Folder File (.pst)
6. select "do not import duplicates"
7. Select Browse. Browse to the location where you saved your pst file
8. Once you select the PST file to import, you will proceed to the next screen. Make sure to select the base folder (the very top of the list). Check the box that says Include subfolders. Select Import items into the same folder in. Choose yourself from the drop down list. Click Finish