Specifies the URL of the image that is used to represent your Office Add-in in the insertion UX and Office Store on high DPI screens.
Add-in type: Content, Task pane, Mail
<HighResolutionIconUrl DefaultValue="string" />
|DefaultValue||string (URL)||required||Specifies the default value for this setting, expressed for the locale specified in the DefaultLocale element.|
For a mail add-in, the icon is displayed in the File > Manage add-ins UI . For a content or task pane add-in, the icon is displayed in the Insert > Add-ins UI.
The image must be in one of the following file formats: GIF, JPG, PNG, EXIF, BMP, or TIFF. For content and task pane apps, the recommended image resolution is 64 x 64 pixels. For mail apps, the image must be 128 x 128 pixels. For more information, see the section Create a consistent visual identity for your app in Create effective listings in AppSource and within Office.