Error 'Unsupported Browser For Mail Merge' while performing a Mail Merge using certain combinations of Office and Windows

The standard Mail Merge feature of Salesforce, not the server-side Extended Mail Merge, does not support certain versions of Word with Windows (see below).
In order to perform mail merges when using, as an example, Word 2010 in Windows 7, the Extended Mail Merge needs to be enabled in the organization. Please contact Salesforce Support to have this feature enabled.

If Extended Mail Merge has already been enabled for the organization, it may be enabled under 'User Interface' in the 'Setup' menu. Please refer to Customizing User Interface Settings for additional information.

This applies to the following combinations of OS and Microsoft Word.

• Windows 8.1 (until January 2023)
• Windows10 + Office 2016