I have 2 computers both with Windows 10 and Windows Live Mail.  One has Open Office while the other newer one has LibraOffice 5.0.  All attachments are received in emails on the system with OpenOffice.  However, file types like .xls are blocked on the system with LibraOffice.

LibraOffice works fine with these file types if I open a file stored on the computer or if I download and open from the web mail (e.g. Outlook or Gmail).  The problem is when these email accounts are defined and uses in the Windows Live client.

I have examined the Settings>System>Default Apps>Choose default apps by file type on both systems.

On the system with OpenOffice, .xls, .xlsx, and others show the Open Office icon but are missing the label OpenOffice Calc.  These file types are accepted by Windows Live Mail.

On the system with LibraOffice, .xls, .xlsx, and others show the LibraOffice icon but are missing the label LibraOffice Calc.  These file types are NOT accepted by Windows Live Mail.

FYI - I don't know if this matters but Settings>System>Default Apps>Set defaults by app, then pick OpenOffice 4.1.1 and pick Choose defaults for this program shows a list of file types and Current default.  For .xls and .xlsx the default says Unknown application.  The same is true for the system with LibraOffice.