Can you accept or decline a meeting invitation in NEW Outlook but not send a response like you can in Classic Outlook?

If you first open the event (double-click on it), then you can RSVP (e.g. decline) with a message.

Dear Sammy_T

Good day!

Thank you for posting to Microsoft Community. We are glad to assist!

Based on your description, I understand you concern with to accept or decline a meeting invitation in NEW Outlook without response.

It doesn't seem feasible to accept or decline a meeting invitation in NEW Outlook without response at this present.

According to your description, I really understand that you are referring to difference in the current feature in New Outlook preview and the classic outlook. And based on my research, I got the same result as yours. Therefore, the feature you are inquiring doesn’t seem feasible in the New Outlook at the moment. However, if you heavily rely on this feature, you may consider toggling out of the new Outlook for Windows preview for now.

Please kindly understand that many functions are not designed at present. I'd suggest you to submit as a feature suggestion in feedback collection directly through your new outlook (Help-->Feedback) Contact support and provide feedback within the new Outlook for Windows - Microsoft Support. Many features of our current products are designed and upgraded based on customers’feedback.

Thanks for your precious time and your understanding would be highly appreciated. Have a nice day!

Best regards,

Allen | Community Moderator