New Outlook keeps changing the name of attachments to random letters and numbers when I try to save the file

Hello Peter. I completely understand your frustration with the new Outlook saving attachments as long, random strings rather than the name of the file you would expect. This has been a known problem for some time. The issue appears to be the way in which Outlook handles attachments when they are shared to OneDrive or handled through its new, unified attachment register. Instead of saving the attachment with the name of the file, Outlook creates a unique identifier, which resembles a hash value, especially when saving an attachment directly from the preview pane or when messages are cloud-linked.

To eliminate the risk of losing the original filename, follow these steps:

• Open the email and right-click on the attachment, and click Save As instead of using the quick download button.
• If it is attached from OneDrive, click Download in the preview section of OneDrive to keep the original file name.
• When saving attachments, do not select them from the message preview pane, as this is where the filename issue occurs most often.

Let me know if this helps or if you have further questions.

Best regards,