To merge outlook archive or .pst files, please follow these steps:
- Close Outlook
- Go to Control Panel > Mail > Data Files
- Single click an "Archive" file, then select "Open File Location" to show the file in Windows Explorer. Repeat this process for each of the archive files.
- Identify the file that you want to designate as the primary .pst file. Move this file to a new location and rename it now (such as "Final Archive" or "New Archive"), if desired.
- Note the file's name and path
- Rename each of the old archives to something unique, such as Old Archive 1.pst; Old Archive 2.pst; etc...
- Create a folder somewhere (such as your desktop) called Old Archives, and move all of your .pst files into this folder.
- IMPORTANT: Do not replace or overwrite archive files that you move into this folder. If prompted, select the option to rename the file.
- Remove all of the "Archives" items from the Account Settings > Data Files window (from step 2)
- Click the Add... button and select the "Final Archive" file you designated in step 4.
- Launch Outlook
- Go to File > Open > Import
- Select to "Import from another program or file" and click Next
- Select the "Outlook Data File (.pst)" option and click Next
- Browse for your first "Old Archive" file, e.g. Old Archive 1.pst
- Select the appropriate option. Most likely you want to not import duplicates.
- Select the destination folder where you would like to import into. This is going to be your "Final Archive" file.
- Allow the import process to complete. This could take anywhere from a few minutes to an entire day, depending on how large your archive file is.
- Delete the Old Archive file you selected in step 14, and repeat the process with the remaining Old Archive files in your Old Archives folder.
Once your archives are merged, it will take a long time to display emails the first time the folder is opened, because the index needs to be rebuilt. It is recommended that you follow the steps here to rebuild your search index: https://iodsupport.unh.edu/index.php?/Knowledgebase/Article/View/72/0/outlook-producing-strange-unexpected-or-incomplete-search-results