Converting Mac Outlook .olm files into .csv format on macOS can be challenging because .olm files use a proprietary archive and database structure that spreadsheet applications cannot open natively. While manual workarounds involve exporting individual folders from Mac Outlook into tab-delimited formats or configuring intermediate IMAP accounts, these methods are tedious, frequently drop folder hierarchies, strip essential metadata, and fail completely on large archives. For a fast, reliable, and offline solution, BitRecover OLM Converter runs completely standalone on Mac and Windows, enabling you to batch-convert .olm files directly into clean, structured .csv spreadsheets while preserving complete MAPI/MIME field mappings (To, From, CC, Subject, Date, Timestamps) and native attachments (PDF, XLS, EML, JPEG, PNG, DOCX).

For this particular requirement, I’d suggest trying BitRecover MSG Duplicate Remover. It is specifically made to locate and remove duplicate MSG items in bulk, so you don’t have to check the files manually one by one. You can add individual MSG files or complete folders and use filtering options to identify duplicates based on the available email details.