Use the Open menu item to open a file for importing into FastEnvelope.
FastEnvelope can open 'TEXT' files. A 'TEXT' file is a specific type of file. You can create 'TEXT' files by using the 'Save As' command and choosing 'TEXT' in most word processors, databases and spreadsheets.
Almost all Macintosh word processors, databases and spreadsheets create 'TEXT' files.
FastEnvelope can import tab or comma delimited files, including merge files.