Attaching a OneDrive file through a web add-in causes recipient access errors in classic Outlook

Last Updated: November 14, 2025

ISSUE

When you use classic Outlook to attach a OneDrive file as a link, where a web add-in is handling send time events, recipients cannot access the links in your message. Performing the following steps will exhibit the issue:

Create a new email message.
Select Include from the ribbon and select Attach File.
Select a file located in your Microsoft OneDrive for Business.
Choose Share Link instead of Attach as Copy.
The link appears highlighted blue.
You select Send and a prompt appears briefly saying "We are still checking if recipients can access links in this message" to check permissions.

Note: If a web add-in is doing the send-time check, you may get the “Checking add-ins” spinner above the Send button. If you are seeing this issue with the built-in link permission check, that could be a different issue.
Prompt resolves to "Recipients can access links in your message".
You send the email, and it successfully sends the message.
The recipient opens the message and is unable to access link.

STATUS: FIXED

This issue is fixed in the following versions:

Version 2512 Build 19430.15000 Beta Channel, Update History for Office Beta Channel
Version 2512 Build 19530.20000 Current Channel Preview, Update History for Office Current Channel (Preview)
Version 2510 Build 19328.20190, Update history for Microsoft 365 Apps
Version 2511 Build 19426.20046
Version 2509 Build 19231.20260
Version 2508 Build 19127.20388
Version 2502 Build 18526.20662