Outlook 365 for Mac - not sending attachments

I'm using Microsoft Outlook for Mac version 16.74.1 (23061800) on a 2021 14-inch M1 Pro MacBook Pro running Ventura 13.4.

I was getting the same issue of attachments looking like they were attached but not being received. I tried multiple updates of Outlook (standard channel, beta channel etc.), uninstalled / reinstalled, turned off antivirus, turned off VPN etc. and no difference. However I noticed that the issue started randomly rather than after an Outlook update - this was the clue that told me the issue was with Outlook itself and this morning I (fingers crossed) have resolved it.

From what I could gather it was a permission issue with macOS. I've had a number of applications (Microsoft and others) all have permissions issues since apple update macOS, so I checked the following in System Settings | Privacy & Security | Full Disk Access and made sure that all Microsoft (and other apps with issues) were included. Outlook wasn't there by default so I added it. I then checked that it had saved by checking the apps in Files and Folders were showing Full Disk Access.

I rebooted Outlook but it still had the same issue so I check permissions to 2 root folders where I know Outlook stores temporary data:

• My user folder (HD > Users > steve)
• My OneDrive folder

On both of these folders I went to 'Get Info' and checked the 'Sharing & Permissions'. I changed it so that 'everyone' and 'Steve (me)' had 'Read & Write' permissions. Closed Outlook and reopened and my test email with attachment was sent and received with the attachment.

Bit of an extreme fix (providing read & write permissions to all isn't great - but I have lots of security enabled to prevent unwanted access so not too bad), but it seems the issue is a permissions issue outside of Outlook. Or at least it was for me.

Hope the above helps someone else!

This is incredibly frustrating. I have 3 emails set up on one outlook and 2 are totally fine sending attachements but my primary I can't attach. How can I talk to someone today to troubleshoot?

I used this information to get Outlook working. I found 2 cases where I needed to set permissions. First - Any folders I attached files from need a Read & Write permission for user Group "Everyone" enabled. Second - For emails received and forwarded, the attachments and embedded images that drop out are stored in this location for the current 2023 version of Outlook - /Users/USERNAME/Library/Group Containers/UBF8T346G9.Office/Outlook/Outlook 15 Profiles/Main Profile/Data/Messages. I just set the permission for Everyone to Read & Write from the Outlook folder down using the Get Info command and then selecting "Apply to enclosed items" to update all sub folders. As soon as this was completed my email started sending attachments and images again for forwarded and newly created emails. It would be good if Microsoft can update Outlook to auto manage this rights piece on MacOS.

This seems to be an issue still. I have a user with O365 Outlook App 16.74.2. He tried sending three attachments and they didn't go thru. They also don't appear in the email in the sent email. Worked from Outlook on the Web though.

I'm having the same issue with the same version 16.74.2.

Steve Cox1's advice does work as a temporary fix but there really needs to be an update from MS as the reduced security of the fix isn't acceptable.