By default (when the Upload Security box is left blank), users can upload any type of file when using the following features:
To limit which file types can be uploaded, add a comma delimited list of allowed file extensions, such as the following:
.docx, .xlsx, .html, .pdf
Important: Be sure to include a period before and a comma after each extension. Spaces are ignored.
With a list of allowed extensions specified, an upload attempt of any file with an unlisted extension will be blocked.