Merge Outlook contact folders from multiple PST files

Consolidating a decade of archives: five PST files, each holding a Contacts folder from a different era of my career. Plenty of the same people appear in several with different details.

How do I merge five contact folders into one sensibly, keeping the newest details where people overlap?

The merge itself is mechanical, the overlap handling is where strategy matters. Work oldest to newest and let newer data win.

1

Attach all five PSTs: File, Open and Export, Open Outlook Data File, repeat per file. Each shows its Contacts folder in the folder pane.

2

Create the destination contacts folder, either in your live mailbox or a fresh consolidation PST.

3

Copy in chronological order, oldest archive first: open its Contacts folder, Ctrl+A, Copy to Folder into the destination. Repeat era by era ending with the newest.

4

Now dedupe with newest first logic: switch the destination to a list view sorted by File As. Duplicate people sit adjacent. Outlook flags nothing automatically, so scan and for each cluster keep the entry with current details, checking the modified date column if unsure, and delete the rest.

For thousands of contacts the manual scan gets rough, and the halfway trick is exporting the merged folder to CSV, deduplicating in Excel with Remove Duplicates keyed on the email column after sorting newest first, then importing the cleaned CSV into a final empty folder. Excel's Remove Duplicates keeps the first occurrence it meets, which is why the newest first sort matters.

1,900 contacts merged, Excel route deduped them to 1,240 keeping the newest rows. One address book at last after ten years.