The glide.attachment.extensions property restricts the file
extensions that users can upload as attachments.
Use this property to improve security by preventing users from uploading harmful
files, such as viruses, as attachments. Also, this capability can prevent the use of
incompatible filetypes. For example, Internet Explorer does not support icons in
.png format. This property does not restrict files based on
the actual file type, but only based on the extension.
In the Attachment limits and behavior section, locate
the List of file extensions (comma-separated) that can be attached to
documents via the attachment dialog property.
Enter the file extensions and click Save.
If no extensions are specified, then all extensions are allowed. However, if
any extensions are specified, all unlisted extensions are restricted. Listed
extensions should not include the dot (.) prefix or spaces after commas. For
example, enter xls,xlsx,doc,docx.