When archiving or deleting emails from OST or PST files, this leaves ‘white space” where the item was, not actually reducing the file’s size. You must perform a ‘Compress” to regain the space AND then defrag the OST/PST file using CONTIG (Since windows defrag hates large files and generally ignores them).
1. Archive, delete or otherwise cleanup outlook data. Try to keep files under 2 gig – even though larger files are supported.
2. Compress data file
a. Tools -> Options -> Mail Settings -> Data Files -> Select Files -> Setting – “Compact Now”
b. This can take a long time, perform during lunch break for 400mb or less, or end of day for large changes.
3. Close Outlook, unload EXE from memory
4. Defrag file, use CONTIG to defrag OST/PST.
5. Repeat for all OTS/PST files in user’s profile.