Outlook Allows All Attachments Despite Level1Add Settings
Outlook may allow access to attachments despite being blocked with the Level1Add registry setting.
This appears to be a bug introduced sometime after the “2005” version of Office 2016. Attachments are shown correctly blocked in 16.0.12827.20470. In versions 16.0.13029.20344, 16.0.13029.20308 (Version 2007), 16.0.13001.20498, 16.0.13001.20384, 16.0.13001.20266 (Version 2006) they are shown as accessible.
This seems to have been remedied in 16.0.13029.20342 (some sort of rollback from 16.0.13029.20344?).