Hi @jon alderson ,
I have a user who has to hold the CTRL button down in order to access their attachment in Outlook 2013.
Based on my tests, I could open the attachment normally via double-click it in my Outlook 2013, which seems to I couldn't reproduce your issue. In order to further confirm if your issue is related to your Outlook client, it's suggested to perform the tests below to check:
- Log in your web mail and open the attachment to test
- Log in other Outlook client that could work normally to test
If the issue occurred on this Outlook client only , what's the version of your Outlook (we could find the detailed information of version via File>Office Account>About Outlook), please first ensure that you have updated to the latest version of Outlook.
Then, could you open the attachment via right-click it> open or download the attachment? If the issue only occurred when you double-click it, based on my research, it may be related to the setting of the double-click speed for your mouse, and we could resolve it via change the setting in your PC, for more detailed information, please refer to this article: Can't open an attachment in Outlook by double-clicking it
If that's invalid, the interference of other programs or add-ins also may affect it, in order to avoid it, it's siggested to close other programs and restart your Outlook in safe mode to check(Windows + R> type "Outlook.exe /safe">enter)
If the issue still exists or you still need further assistance, please provide me with more information about your issue, so that I would provide you with more targeted help.
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