Migrate from MS Office
Can I use the Mail Merge Add-on with my Microsoft Word Documents and Microsoft Excel Spreadsheets?
If you try to mail merge from a Microsoft Word document or Microsoft Excel spreadsheet, you will note that there is no Add-ons option on the menu bar. To run the Mail Merge add-on, you first need to convert your Word document to Google Docs format or your Excel spreadsheet to Google Sheets format.
From your Word document or Excel spreadsheet, click File > Save as Google Docs/Sheets. This will create and open a copy of your file in Google Docs/Sheets format, from which you can run the Mail Merge add-on as normal.
NOTE: If you are merging from Google Docs, the add-on will automatically convert your Microsoft Excel source spreadsheet into Google Sheets format; there is no need to do this manually prior to merging. Your Excel spreadsheet will appear in the Select a Spreadsheet File dialog box (see screenshot below).
During the mail merge process, your original Excel spreadsheet will be preserved and a copy of your spreadsheet will be created automatically in Google Sheets format.