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: We’ve deployed our immediate fix to our internal testing environment, where it’s undergoing validations to ensure it successfully reduces the incorrect calls to add and remove attachments to provide relief to users. We anticipate this may be ready for deployment to affected users by mid-October 2023. In parallel, we’re continuing to develop a long-term fix for deployment to accompany the prior fixes to fully resolve the issue for all users.
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: Wednesday, October 11, 2023, at 8:00 PM UTC
