Outlook for Mac not sending attachments

Dan Northrop 40 Reputation points

I've only been on Outlook for a few weeks as we recently swapped to Microsoft exchange etc. However, time and time again, I send an email with an attachment and the client comes back to me to say that it's not attached. It seems that there are a few random posts around the net about this, but I cannot find the fix.

Anyone on here know of a way? It's happening on more than 50% of my emails with attachments.

Im on version 16.75.1 which is the latest.

A family of Microsoft email and calendar products.
2,619 questions
Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
4,041 questions
{count} votes

Accepted answer
  1. ChristyZhang-MSFT 18,711 Reputation points Microsoft Vendor

    Hi @Dan Northrop ,

    Welcome to our forum!

    According to your description, seems like it's related to a transient backend incident. If you are the administrator, you might be able to see the EX637339 in the Issue history of the Service Health Dashboard:


    As mentioned in the above, please verify if you’ve encountered this problem in Outlook for Mac by reviewing their Sent Items to validate if a sent message contains an attachment. If you don't see the attachment, you can reply to the message in their Sent Items folder to reattach and send the message again.

    Please be patient and stay tuned for the update.

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

    1 person found this answer helpful.

1 additional answer

Sort by: Most helpful
  1. workforce45 621 Reputation points

    Hi Dan,

    We first need to take a backup of Outlook data file in Mac. Please refer an article mentioned below.

    Export or backup email, contacts, and calendar to an Outlook .pst file - Microsoft Support


    We can try Basic Troubleshooting for Microsoft Outlook on Mac

    It is a most basic check that you can perform before testing any other method. Go to the Outlook menu and check if the Work Offline option is selected or not.

    Click on Tools > Accounts > check the color of exchange account, it should not be orange/amber. If yes, there is a connection problem.

    Update outlook for mac, click help > check for updates.

    In the Microsoft Autoupdate wizard > select Automatically.

    We can also try to generate an App Password for a configured email account and reconfigure an account on Outlook.


    Rebuild Office database.

    Close Outlook for Mac and other Microsoft Office applications.

    Locate Microsoft Database Utility. Its default location is Applications/Microsoft Office {version/year}/Office.

    Launch the utility and select the identity of the database you want to rebuild. Then click Rebuild.

    Rebuild the Office database - Microsoft Support


    Reset Outlook on Mac

    Quit all Office applications.

    Open Finder and go to ~/Library/Group Containers/UBF8T346G9.Office/User Content/Templates, move Normal.dotm to Desktop.

    Go to ~/Library/Preferences, locate the files com.microsoft.outlook.plist and com.microsoft.Office.plist, move them to the Desktop (Outlook will rebuild them).

    Restart Outlook and Machine

    Please update with your findings.



    0 comments No comments