Email attachments are blocked on Server but not Workstations

Question

Email Attachments - File Download / Blocked / Open Issue My client has a series of workstations within his business operated by staff. He also operates a machine as the Server and it is currently running Windows Server 2016. The client operates his MS 365 email accounts from the Server. Beginning Monday 20/03/23 the following issue has occurred. Documents and images attached to emails received in Outlook can be opened without a problem from within Outlook but if they’re saved to the Server they can no longer be opened. The client must right click on the file concerned in File Explorer, click the General tab, click Properties and tick the “Unblock” box next to the Security text “This file came from another computer and might be blocked to help protect this computer”. This issue is also occurring with files downloaded/copied to the server from emails received before 20/03/23. The following is also relevant: Attachments to emails received in Outlook that are saved/copied to workstations on the network other than the Server can be opened without issue. If those attachments/documents are then copied back to the Server they can also be opened without issue. We understand the Server has policies applied to it by Azure which is why it is different to his workstations. We need to know if Microsoft has changed the security rules that are automatically applied to the Server which means this machine is now acting differently to his workstations. Either that or is there some other reason for this to have started happening around 20/03/23 and how can it be resolved?

Answer 1

Hi @Support - David Floyd ,

From my searches, Windows classifies certain files as unsafe downloads and attachments by identifying the files type and the security settings for each file. For doing this, it uses the Attachment Manager in Windows, which is a service that gets activated whenever you receive an e-mail message with an attachment and from unsafe files that you might save from the Internet.

You can disable the Attachment Manager using Windows Registry, refer to this article: https://www.technewstoday.com/this-file-came-from-another-computer-and-might-be-blocked/

(Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.)

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