Whenever our Exchange users (using Outlook 2013) try to open an attachment in their mail which has been sent by a user in the organization a security popup appears telling them that files from the internet may be harmful.
The user has to press next to open the file.
is there a way to disable this for users sending from the internal organization? I'm sure it should be possible using group policies but I haven't found a way how to accomplish this.
The internal domain has been added to the intranet zone mapping using GPO.
Help would be much appreciated!