MSOffice is a program so I would have expected to locate it under 'Program Files' Try: C:\Program Files\Microsoft Office\Office16 or whatever Office folder exists there Select 'WinWord.exe'

Thanks, Toad-Hall I did look there and in Programs (x86) but no sign of Office. So I searched for winword which lead me down the pathway of appdata etc but it would not let me link it to the winword file I found at the end. Its a Lenovo computer with an AMD Ryzen 5 chip so may be they have hidden it away somewhere else??

Hi Toad-Hall, In Tbird I have accidentally selected the option TWINUI to open a .doc attachment and it opened in Word! A bit of a surprise since to my mind TWINUI is not an intuitive name for Word which is why I did not try it before. Anyway that seems to have solved my immediate problem. Thanks for your help, Thunderstone

Hi I've just located some info which I discussed with someone else about two and half years ago. Although it seems you have already found the same result.

Info for anyone who reads this question: Has MS Windows 10 changed the way files are opened? Yes :) Something to do with sandboxing applications, which prevents them being run from another application. But they did provide a means of getting it to work. So instead of selecting the app you desire, select the really obvious Action name TWINUI.

'TWinUI' is short for 'Tablet Windows User Interface'.

In Thunderbird: Tools > Options > Attachments > Incoming tab or Menu icon > Options > Options > Attachments > Incoming tab

If Microsoft Word document is listed in the 'Content Type' column:

• click on the 'Action' to see a drop down list.
• select : 'Use Other'
• a 'Select Helper Application' window opens.
• select TWINUI.

This refers to the windows 10 shell and chooses the system default application for the file type.

• click on OK
• Click on OK to close and save Options.

Additional info: NOTE: If a user has Office Starter, Home, or Student Edition installed, there is no WinWord.exe , since it uses a Client Virtualization Handler. The path to launch a .DOC (.DOCX) files could be something like this: "C:\Program Files (x86)\Common Files\microsoft shared\virtualization handler\cvh.exe" "Microsoft Word Starter 2010 9014006604190000" /n "%1"

• http://www.actualinstaller.com/help/winword.html

Thanks Toad-Hall If anyone from Microsoft office is reading this, how about changing the name TWINUI to something more user friendly? Over and out, Thunderstone