Recently, we have some users which suddenly got this massege: "Outlook blocked access to the following potentially unsafe attachments" (outlook 2010 plus)
I had tried all of this: https://support.microsoft.com/en-us/help/829982/outlook-blocked-access-to-the-following-potentially-unsafe-attachment but nothing had changed...
We recently had the same issue, when I removed KB3203467 (Security Update for Microsoft Outlook 2010) - this resolved the issue immediately.