An administrator asked about a policy solution to prevent users from clicking on links in email.
While you can't prevent users from clicking on links, you can take advantage of a fairly common problem to make the links unusable. This won't stop clever users from copying the links and pasting them into the browser but it will slow them down, hopefully, slow them down enough to make them think.
Most users want to fix the “This operation has been cancelled due to restrictions in effect on this computer.” error, but you can force this error in Outlook (and other programs) by editing a registry key:
Rename or delete the command key found at
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\htmlfile\shell\open\command
Once you do this, users will get an annoying error when they click on links in email and other applications. Links will work as expected within the browser and users can copy and paste the links into a browser to view them.
On a related note, its also possible to block users from opening specific attachments, either by blocking them completely, as if they were exe attachments, or by forcing users to save them to the hard drive before opening. We have instructions for using the Level1Add and Level1Remove keys at Block Additional Attachment Types.
Dhruva Kudva says
Does not seem to work in Outlook C2R versions as well. Do we have any other options available?
Diane Poremsky says
No, this is the only way I'm aware to block it.
Eric says
This works on Outlook 2010 but not on Outlook 2019 desktop version. Any ideas? Thank you.
Diane Poremsky says
No, not right now. I need to test it.
Eric says
It would be great to have a solution on this before Outlook 2010 sunsets in October and we have to move to Outlook 2019.
Eric says
Still nothing on this? The only solution I have found is to set IE as default and then block IE thru group policy. The disadvantage is that it blocks links everywhere not just outlook.
Diane Poremsky says
Yeah, there is no good way to prevent using from clicking links. You would need to scan the messages at the server and remove the links.
vito romano says
Hi, I love the reg hack for disabling links in emails, but is there a way to disable these links on a user account and not just on a machine? We need to target specific users.
Thanks
Vito
Diane Poremsky says
If users log into computers, you can use group policy or a logon script to set it.
If you use office 365 and Advanced threat protection, you can also block links per user.