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HatredNamiki's avatar
HatredNamiki
Copper Contributor
Mar 26, 2026

Outlook contact CSV import corrupts existing contacts without warning

Outlook (classic) corrupts existing contacts during CSV import without any warning.

 

When I re-import a CSV exported by Outlook itself (UTF-8 with BOM),

the contacts lose their names and email addresses and appear as

“Name not available”.

 

Using the exact same CSV content re-encoded as Shift-JIS imports correctly.

 

This behavior is reproducible and cannot be prevented by user actions.

It appears to be a defect or a flawed design in Outlook’s CSV import logic.

Please investigate and provide an official explanation.

1 Reply

  • Hi HatredNamiki, before trying another import, export and back up the current contacts so you have a rollback point. CSV imports are very sensitive to column mapping, encoding, and duplicate handling, even when the CSV originally came from Outlook. I would test with two or three contacts in a separate contacts folder first, manually verify the field mapping, and avoid importing over existing contacts until the mapping is proven. If Outlook is corrupting its own export/import format, that is worth reporting with a sample CSV that has private data removed.