In Egnyte, you can easily apply Watermarks to files viewed through a preview-only file link. Watermarks can be set at any time and will apply to every link with disabled download, regardless of when created (so it will apply to both links created before enabling this feature and newly created ones).
Turning on Watermarks
To enable the Watermarking feature on your domain, go to Configuration > Settings > General section and enable the Watermark files option.
The Admin can provide one text for the whole domain, and it can contain a special code {{viewerIpAddress}} which will be dynamically replaced with the viewer's IP address.
Preview
When watermarks are enabled for the domain, then the watermark text will be displayed diagonally in the preview for all files shared with the No Download option (preview-only). The {{viewerIpAddress}} will be replaced with the viewer's IP address. The text will be automatically scaled to the preview size.