Sophos for Microsoft SharePoint: error reported when uploaded file is blocked

Issue
Uploaded file is blocked by SharePoint with the following message:

Error The following file(s) have been blocked by the administrator <>

This is not a bug. The file is blocked by SharePoint itself, not by Sophos for Microsoft SharePoint.

Sophos product and version
Sophos for Microsoft SharePoint

What to do

Edit the SharePoint configuration from: Administrative Tools|SharePoint Central Administration|Operations|Block file types

Technical information
The SharePoint “Block file types” uses the file extension (i.e.. will block executables only if they have an EXE extension, not if they have been renamed with another extension that is not in the list). The SharePoint blocking by extension is triggered before Sophos for Microsoft SharePoint can scan the file. For true file type detection or more complex filename patterns use the Sophos for Microsoft SharePoint on-access content policy configuration.