I have a dump of contacts from a different program, it started life as an Excel (old 2003 format xls) file. I need to massage this data to work in modern mail programs, the eventual target is ...

Gmail offers a dedicated import tool for mail and contacts, but it cannot import the other data included in a PST file, like calendar appointments.

In Gmail, click the "Gmail" drop-down menu and choose "Contacts." Click "More" and choose "Import" to open the Import Contacts dialog box.