When performing an HTML custom query in the Integration for Microsoft Outlook 2021, it is possible the custom query cannot perform the search. If your HTML custom query e-form uses CSS or JavaScript, then the e-form cannot be rendered in the Integration for Microsoft Outlook 2021 user interface as these languages are not supported for rendering. To fix this issue, you must add the following element within the <head> tag of every e-form you want to use with the Integration for Microsoft Outlook 2021:
<meta http-equiv="X-UA-Compatible" content="IE=edge">