There could be many possible reasons that could lead to attachment issues in Outlook. This includes incorrect Outlook settings, file incompatibility, incorrect mail format, etc. Try resetting Outlook ...

Outlook for Windows 11 now has the ability to add multiple recipients to replies, access attachments offline, and more.

I'm guessing this is probably another thing to add to the list of failures with Outlook 2010. When opening a file in Windows Explorer, you can right click and choose to Open With, that is you can ...