Outlook Classic does not render emails that outlook web does

Dear @Bill Hopgood,

Based on your description, this behavior is expected due to differences in the rendering engines used by Outlook on the web (OWA) and Outlook Classic for Windows.

Classic for Windows uses the Microsoft Word rendering engine to display HTML email content. Because of this architectural difference, certain HTML elements, CSS styles, and modern web design features that render correctly in OWA may not display as expected in Outlook Classic.

It is also worth noting that OWA and New Outlook for Windows share a similar modern web-based architecture and rendering approach. As a result, HTML emails often render consistently between those clients. In contrast, Outlook Classic uses the Word rendering engine, which supports a different subset of HTML and CSS capabilities. Therefore, if an email renders correctly in OWA and New Outlook but not in Outlook Classic, the behavior is typically related to Outlook Classic's rendering limitations rather than an email delivery or Exchange Online issue.

If the rendering difference is causing a significant business impact and the email content follows standard HTML practices, you may submit feedback to the Outlook product team through Help > Feedback in Outlook or via the Microsoft Feedback Portal. While I cannot guarantee a product change, customer feedback helps Microsoft understand the impact and prioritize future improvements.

I hope information above meet your expectations, feel free to reach out if you have any other questions.

Note: Please follow the steps in the forum documentation to enable e-mail notifications if you want to receive the related email notification for this thread.