---
title: "Mailbox requirement set 1.16 now available for Outlook add-ins"
url: https://daily.dev/posts/mailbox-requirement-set-1-16-now-available-for-outlook-add-ins-4jiuny2r3
source_url: https://devblogs.microsoft.com/microsoft365dev/mailbox-requirement-set-1-16-now-available-for-outlook-add-ins
type: article
source: "DevBlogs"
published: 2026-07-01T08:55:48.343Z
updated: 2026-07-01T08:56:09.650Z
reading_time: 2
upvotes: 0
comments: 0
language: en
---

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# Mailbox requirement set 1.16 now available for Outlook add-ins

**[DevBlogs](https://daily.dev/sources/devblogs)** · 2 min read · 0 upvotes · 0 comments

## Summary

Mailbox requirement set 1.16 is now generally available for Outlook add-ins. Key additions include the OnMessageDecrypt event for automatic decryption of protected messages in event-based workflows, a new API to detect EWS token support in on-premises organizations, a contentId property for identifying inline attachments, an expanded Recipients API returning up to 1,000 recipients per field, and a larger SessionData limit of 2,621,440 characters per add-in.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://devblogs.microsoft.com/microsoft365dev/mailbox-requirement-set-1-16-now-available-for-outlook-add-ins>

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