[Outlook] (metadata) Document SessionData API (#5035)

* Document SessionData API

* Fix tabbed layout

* Fix link

Author: samantharamon

docs/outlook/delegate-access.md

@@ -248,7 +248,7 @@ If an admin hid a user or shared mailbox address from an address list, such as t
 
 ### Sync across shared folder clients
 
-A delegate's updates to the owner's mailbox are usually synced across mailboxes immediately. However, if Microsoft Graph operations were used to set an extended property on an item, such changes could take some time to sync. To avoid a delay, we recommend you instead use the [CustomProperties](/javascript/api/outlook/office.customproperties) object and related APIs. To learn more, see the "Custom data per item in a mailbox: custom properties" section of [Get and set metadata in an Outlook add-in](metadata-for-an-outlook-add-in.md#custom-data-per-item-in-a-mailbox-custom-properties).
+A delegate's updates to the owner's mailbox are usually synced across mailboxes immediately. However, if Microsoft Graph operations were used to set an extended property on an item, such changes could take some time to sync. To avoid a delay, we recommend you instead use the [CustomProperties](/javascript/api/outlook/office.customproperties) object and related APIs. To learn more, see the "Custom properties" tab of [Get and set metadata in an Outlook add-in](metadata-for-an-outlook-add-in.md?tabs=custom-properties).
 
 ## See also
 

docs/outlook/internet-headers.md

@@ -1,7 +1,7 @@
 ---
 title: Get and set internet headers
 description: How to get and set internet headers on a message in an Outlook add-in.
-ms.date: 10/17/2024
+ms.date: 02/11/2025
 ms.topic: how-to
 ms.localizationpriority: medium
 ---
@@ -12,10 +12,10 @@ ms.localizationpriority: medium
 
 A common requirement in Outlook add-ins development is to store custom properties associated with an add-in at different levels. At present, custom properties are stored at the item or mailbox level.
 
-- Item level - For properties that apply to a specific item, use the [CustomProperties](/javascript/api/outlook/office.customproperties) object. For example, store a customer code associated with the person who sent the email.
+- Item level - For properties that apply to a specific item that need to be accessed during subsequent Outlook sessions, use the [CustomProperties](/javascript/api/outlook/office.customproperties) object. For example, store a customer code associated with the person who sent the email. If properties for a specific item are only needed during the current compose session, use the [SessionData](/javascript/api/outlook/office.sessiondata) object.
 - Mailbox level - For properties that apply to all the mail items in the user's mailbox, use the [RoamingSettings](/javascript/api/outlook/office.roamingsettings) object. For example, store a user's preference to show the temperature in a particular scale.
 
-Both types of properties aren't preserved after the item leaves the Exchange server, so the email recipients can't get any properties set on the item. Therefore, developers can't access those settings or other Multipurpose Internet Mail Extensions (MIME) properties to enable better read scenarios.
+These types of properties aren't preserved after the item leaves the Exchange server, so the email recipients can't get any properties set on the item. Therefore, developers can't access those settings or other Multipurpose Internet Mail Extensions (MIME) properties to enable better read scenarios.
 
 In Exchange on-premises environments, while there's a way for you to set the internet headers through Exchange Web Services (EWS) requests, in some scenarios, making an EWS request won't work. For example, in Compose mode on Outlook desktop, the item ID isn't synced on `saveAsync` in cached mode.
 

docs/outlook/limits-for-activation-and-javascript-api-for-outlook-add-ins.md

@@ -1,7 +1,7 @@
 ---
 title: Limits for activation and API usage in Outlook add-ins
 description: Be aware of certain activation and API usage guidelines, and implement your add-ins to stay within these limits.
-ms.date: 07/18/2024
+ms.date: 02/11/2025
 ms.topic: best-practice
 ms.localizationpriority: medium
 ---
@@ -25,6 +25,7 @@ Each Outlook client enforces certain limits in the JavaScript object model, as d
 |:-----|:-----|:-----|:-----|
 |Custom properties|2,500 characters|[CustomProperties](/javascript/api/outlook/office.customproperties) object<br/><br/>[Item.loadCustomPropertiesAsync](/javascript/api/requirement-sets/outlook/preview-requirement-set/office.context.mailbox.item#methods) method|Limit for all custom properties for an appointment or message item. All the Outlook clients return an error if the total size of all custom properties of an add-in exceeds this limit.|
 |Roaming settings|32 KB number of characters|[RoamingSettings](/javascript/api/outlook/office.roamingsettings) object<br/><br/>[Context.roamingSettings](/javascript/api/office/office.context#office-office-context-roamingsettings-member) property|Limit for all roaming settings for the add-in. All the Outlook clients return an error if your settings exceed this limit.|
+|Session data|50,000 characters|[Office.SessionData](/javascript/api/outlook/office.sessiondata)<br/><br/>[Item.sessionData](/javascript/api/requirement-sets/outlook/preview-requirement-set/office.context.mailbox.item#methods) method|For a specific mail item, the limit of an entire SessionData object per add-in.|
 |Internet headers|256 KB per message in Exchange Online<br/><br/>Header size limit determined by the organization's administrators in Exchange on-premises|[InternetHeaders.setAsync](/javascript/api/outlook/office.internetheaders) method|The total size limit of headers that can be applied to a message.|
 |Exchange Web Services|5 MB number of characters in Outlook on the web, on Windows (starting in Version 2303 (Build 16225.10000)), on Mac (starting in Version 16.73 (23042601)), and in [new Outlook on Windows](https://support.microsoft.com/office/656bb8d9-5a60-49b2-a98b-ba7822bc7627)<br><br>1 MB of characters in earlier versions of Outlook on Windows (classic) and on Mac|[Mailbox.makeEwsRequestAsync](/javascript/api/outlook/office.mailbox#outlook-office-mailbox-makeewsrequestasync-member(1)) method|Limit for a request or response to a `Mailbox.makeEwsRequestAsync` call.|
 |Item multi-select|100 messages|[Mailbox.getSelectedItemsAsync](/javascript/api/outlook/office.mailbox#outlook-office-mailbox-getselecteditemsasync-member(1)) method|The maximum number of selected messages on which an Outlook add-in can activate.|