[Outlook] (Smart Alerts) Document character limit of dialog message (#5044)

Author: samantharamon

docs/outlook/onmessagesend-onappointmentsend-events.md

@@ -1,7 +1,7 @@
 ---
 title: Handle OnMessageSend and OnAppointmentSend events in your Outlook add-in with Smart Alerts
 description: Learn about the Smart Alerts implementation and how it handles the OnMessageSend and OnAppointmentSend events in your event-based Outlook add-in.
-ms.date: 02/12/2025
+ms.date: 02/13/2025
 ms.topic: concept-article
 ms.localizationpriority: medium
 ---
@@ -222,7 +222,7 @@ Because the `OnMessageSend` and `OnAppointmentSend` events are supported through
 
 In addition to these constraints, only one instance each of the `OnMessageSend` and `OnAppointmentSend` event can be declared in the manifest. If you require multiple `OnMessageSend` or `OnAppointmentSend` events, you must declare each one in a separate add-in.
 
-While you can change the Smart Alerts dialog message and **Don't Send** button to suit your add-in scenario, the following can't be customized.
+The Smart Alerts dialog message must be 500 characters or less. While you can change the dialog message and **Don't Send** button to suit your add-in scenario, the following can't be customized.
 
 - The dialog's title bar. Your add-in's name is always displayed there.
 - The font or color of the dialog message. However, you can use Markdown to format certain elements of your message. For a list of supported elements, see [Limitations to formatting the dialog message using Markdown](#limitations-to-formatting-the-dialog-message-using-markdown).