[Outlook] (on-send) Improve Smart Alerts note (#5172)

* Reframe Smart Alerts message and fix images

* Reword

* Emphasize supported manifest types

* Update ms.date

Author: samantharamon

docs/images/block-on-send-subject-cc-inforbar.png renamed to docs/images/block-on-send-subject-cc-infobar.png

@@ -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: 03/11/2025
+ms.date: 05/22/2025
 ms.topic: concept-article
 ms.localizationpriority: medium
 ---
@@ -340,8 +340,9 @@ While Smart Alerts and the [on-send feature](outlook-on-send-addins.md) provide
 |-----|-----|-----|
 |**Minimum supported requirement set**|[Mailbox 1.12](/javascript/api/requirement-sets/outlook/requirement-set-1.12/outlook-requirement-set-1.12)|[Mailbox 1.8](/javascript/api/requirement-sets/outlook/requirement-set-1.8/outlook-requirement-set-1.8)|
 |**Supported Outlook clients**|<ul><li>Windows (new and classic)</li><li>Web browser (modern UI)</li><li>Mac (new UI)</li></ul>|<ul><li>Windows (classic)</li><li>Web browser (modern and classic UI)</li><li>Mac (new and classic UI)</li></ul>|
-|**Supported events**|**Add-in only manifest**<ul><li>`OnMessageSend`</li><li>`OnAppointmentSend`</li></ul><br>**Unified manifest for Microsoft 365**<ul><li>`"messageSending"`</li><li>`"appointmentSending"`</li></ul>|**Add-in only manifest**<ul><li>`ItemSend`</li></ul><br>**Unified manifest for Microsoft 365**<ul><li>Not supported</li></ul>|
-|**Manifest extension property**|**Add-in only manifest**<ul><li>`LaunchEvent`</li></ul><br>**Unified manifest for Microsoft 365**<ul><li>`"autoRunEvents"`</li></ul>|**Add-in only manifest**<ul><li>`Events`</li></ul><br>**Unified manifest for Microsoft 365**<ul><li>Not supported</li></ul>|
+|**Supported manifest types**|<ul><li>Unified manifest for Microsoft 365</li><li>Add-in only manifest</li></ul>|Add-in only manifest|
+|**Supported events**|**Add-in only manifest**<ul><li>`OnMessageSend`</li><li>`OnAppointmentSend`</li></ul><br>**Unified manifest for Microsoft 365**<ul><li>`"messageSending"`</li><li>`"appointmentSending"`</li></ul>|`ItemSend`|
+|**Manifest extension property**|**Add-in only manifest**<ul><li>`LaunchEvent`</li></ul><br>**Unified manifest for Microsoft 365**<ul><li>`"autoRunEvents"`</li></ul>|`Events`|
 |**Supported send mode options**|<ul><li>prompt user</li><li>soft block</li><li>block</li></ul><br>To learn more about each option, see [Available send mode options](#available-send-mode-options).|Block|
 |**Maximum number of supported events in an add-in**|One `OnMessageSend` and one `OnAppointmentSend` event.|One `ItemSend` event.|
 |**Add-in deployment**|Add-in can be published to AppSource if its send mode property is set to the **soft block** or **prompt user** option. Otherwise, the add-in must be deployed by an organization's administrator.|Add-in can't be published to AppSource. It must be deployed by an organization's administrator.|

docs/outlook/onmessagesend-onappointmentsend-events.md

@@ -1,16 +1,26 @@
 ---
 title: On-send feature for Outlook add-ins
 description: Provides a way to handle an item or block users from certain actions, and allows an add-in to set certain properties on send.
-ms.date: 04/12/2024
+ms.date: 05/22/2025
 ms.localizationpriority: medium
 ---
 
 # On-send feature for Outlook add-ins
 
-The on-send feature for Outlook add-ins provides a way to handle a message or meeting item, or block users from certain actions, and allows an add-in to set certain properties on send.
+> [!IMPORTANT]
+>
+> We recommend using [Smart Alerts](onmessagesend-onappointmentsend-events.md) instead of the on-send feature to check that certain conditions are met before a mail item is sent. Smart Alerts was released in [requirement set 1.12](/javascript/api/requirement-sets/outlook/requirement-set-1.12/outlook-requirement-set-1.12) and introduced the `OnMessageSend` and `OnAppointmentSend` events.
+>
+> Smart Alerts provides the following benefits.
+>
+> - It offers [send mode options](onmessagesend-onappointmentsend-events.md#available-send-mode-options) when you want to provide your users with optional recommendations instead of mandatory conditions, so that they won't be unnecessarily blocked from sending messages. For example, with the **soft block** option, users can still send messages even if the add-in is unavailable during an outage. This option isn't supported by the on-send feature.
+> - It allows your add-in to be published to AppSource if the send mode property is set to the **prompt user** or **soft block** option. To learn more about publishing an event-based add-in, see [AppSource listing options for your event-based Outlook add-in](autolaunch-store-options.md).
+>
+> The on-send feature should only be used to support older Outlook versions that don't support the Smart Alerts feature. For improved security, we encourage users to upgrade to the latest version of Outlook.
+>
+> For more information on the differences between Smart Alerts and the on-send feature, see [Differences between Smart Alerts and the on-send feature](onmessagesend-onappointmentsend-events.md#differences-between-smart-alerts-and-the-on-send-feature). [Try out Smart Alerts by completing the walkthrough](smart-alerts-onmessagesend-walkthrough.md).
 
-> [!NOTE]
-> The on-send feature isn't supported in add-ins that use the [Unified manifest for Microsoft 365](../develop/unified-manifest-overview.md). Achieve similar effects by using [event-based activation](autolaunch.md) and implementing a handler for the **OnMessageSend** or **OnAppointmentSend** events, or both. See also the note below about Smart Alerts.
+The on-send feature for Outlook add-ins provides a way to handle a message or meeting item, or block users from certain actions, and allows an add-in to set certain properties on send.
 
 For example, use the on-send feature to:
 
@@ -21,14 +31,6 @@ The on-send feature is triggered by the `ItemSend` event type and is UI-less.
 
 For information about limitations related to the on-send feature, see [Limitations](#limitations) later in this article.
 
-> [!NOTE]
-> [Smart Alerts](onmessagesend-onappointmentsend-events.md) is a newer version of the on-send feature. It was released in [requirement set 1.12](/javascript/api/requirement-sets/outlook/requirement-set-1.12/outlook-requirement-set-1.12) and introduced the `OnMessageSend` and `OnAppointmentSend` events. Similar to the on-send feature, Smart Alerts enables your add-in to check that certain conditions are met before a mail item is sent. Smart Alerts differentiates itself from the on-send feature as follows:
->
-> - It offers [send mode options](onmessagesend-onappointmentsend-events.md#available-send-mode-options) when you want to provide your users with optional recommendations instead of mandatory conditions.
-> - It allows your add-in to be published to AppSource if the send mode property is set to the **prompt user** or **soft block** option. To learn more about publishing an event-based add-in, see [AppSource listing options for your event-based Outlook add-in](autolaunch-store-options.md).
->
-> For more information on the differences between Smart Alerts and the on-send feature, see [Differences between Smart Alerts and the on-send feature](onmessagesend-onappointmentsend-events.md#differences-between-smart-alerts-and-the-on-send-feature). We invite you to [try out Smart Alerts by completing the walkthrough](smart-alerts-onmessagesend-walkthrough.md).
-
 ## Supported clients and platforms
 
 The following table shows supported client-server combinations for the on-send feature, including the minimum required Cumulative Update where applicable. Excluded combinations are not supported.
@@ -61,11 +63,11 @@ Validation is done on the client side in Outlook when the send event is triggere
 
 The following screenshot shows an information bar that notifies the sender to add a subject.
 
-![An error message prompting the user to enter a missing subject line.](../images/block-on-send-subject-cc-inforbar.png)
+:::image type="content" source="../images/block-on-send-subject-cc-infobar.png" alt-text="An error message prompting the user to enter a missing subject line.":::
 
 The following screenshot shows an information bar that notifies the sender that blocked words were found.
 
-![An error message telling the user that blocked words were found.](../images/block-on-send-body.png)
+:::image type="content" source="../images/block-on-send-body.png" alt-text="An error message notifying the user that blocked words were found.":::
 
 ## Limitations
 
@@ -77,7 +79,7 @@ The on-send feature currently has the following limitations.
   > [!IMPORTANT]
   > When running `npm run validate` to [validate your add-in's manifest](../testing/troubleshoot-manifest.md), you'll receive the error, "Mailbox add-in containing ItemSend event is invalid. Mailbox add-in manifest contains ItemSend event in VersionOverrides which is not allowed." This message appears because add-ins that use the `ItemSend` event, which is required for this version of the on-send feature, can't be published to AppSource. You'll still be able to sideload and run your add-in, provided that no other validation errors are found.
 
-- **Manifest** – Only one `ItemSend` event is supported per add-in. If you have two or more `ItemSend` events in a manifest, the manifest will fail validation.
+- **Manifest** – The on-send feature is only supported in add-ins that use the [add-in only manifest](../develop/add-in-manifests.md). It isn't supported in add-ins that use the [unified manifest for Microsoft 365](../develop/unified-manifest-overview.md). In the add-in only manifest, only one `ItemSend` event is supported per add-in. If you have two or more `ItemSend` events in a manifest, the manifest will fail validation.
 - **Performance** – Multiple roundtrips to the web server that hosts the add-in can affect the performance of the add-in. Consider the effects on performance when you create add-ins that require multiple message- or meeting-based operations.
 - **Send Later** (Mac only) – If there are on-send add-ins, the **Send Later** feature will be unavailable.