Could you please share a screenshot of your flow’s configuration? Do you want to send a certificated email to Inbox folder of Outlook for triggering the flow?
Use the “When a new email arrives” trigger to create a flow that runs when one or more of these email properties (Folder, To, From, Importance, Has Attachment and Subject Filter) match criteria you provide.
The Certificated property may not trigger the flow in Microsoft Flow currently. More details about “Trigger a flow with email”, please check the following article: