Some users’ email with attachments sent from Outlook for Mac may be delivered without attachments

Title: Some users’ email with attachments sent from Outlook for Mac may be delivered without attachments
User impact: Users’ email with attachments sent from Outlook for Mac may be delivered without attachments.
More info: Users can verify if they’ve encountered this problem in Outlook for Mac by reviewing their Sent Items to validate if a sent message contains an attachment. If users don’t see the attachment, they can reply to the message in their Sent Items folder to reattach and send the message again.
Current status: Deployment of the initial fix is complete, and our testing indicates that the majority of messages with attachments from the past week were received as expected; however, some impact is ongoing that we anticipate will need to be addressed with our long-term fix. We’re continuing our development of the long-term fix to resolve the remaining instances of impact, which is a complex task that involves several service components and therefore requires additional time for development to ensure no unintended consequences arise from its implementation. We’ll provide a timeline for the final fix deployment and remediation of impact as it becomes available.
Scope of impact: This issue is specific to a very small percentage of users’ email with attachments sent from Outlook for Mac.
Start time: Monday, July 10, 2023, at 8:08 PM UTC
Root cause: A conflict occurring with how our service detects attachment IDs before sending email in Outlook for Mac is resulting in the service removing attachments on sending email.
Next update by: Tuesday, November 7, 2023, at 10:00 PM UTC