MIME Type Validation

Validate files by their MIME type using EnableMimeCheck="true". This checks the actual content type rather than just the file extension, providing stronger security.

<au:AjaxFileUpload ID="Uploader1" runat="server"
    EnableMimeCheck="true"
    AllowedExtensions=".jpg,.png,.gif,.pdf"
    ButtonText="Select File (images/PDF only)"
    AutoUpload="true"
    ShowProgress="true" />

MIME checking verifies the actual file content matches the extension, preventing renamed files from bypassing extension-based validation.