In previous versions of Office, I could specify my trusted protocol, to avoid the trusted protocol dialog when clicking a custom link.

It used to be here:

HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\<version>\Common\Security\Trusted Protocols\All Applications\myprotocol:

But setting this:

HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16\Common\Security\Trusted Protocols\All Applications\myprotocol:

Does not work.

Anybody knows how to specify trusted protocol in latest Office 365?


@MojoDK, I fear you've just got your version number wrong. You've got 16 and it should be 16.0. Using the corrected version, I was able to disable warning messages for a custom protocol in Office365.

For people in a hurry

Download and edit this .reg file according to the enclosed instructions with something like Notepad++. Once you've edited it, running the file will create any necessary registry keys for you.

For people... not in a hurry

Below are some of my own recommendations for doing it manually, along with Microsoft's instructions on how to disable the warnings on a protocol-by-protocol basis.

How to enable or disable hyperlink warnings per protocol

To disable the display of security warnings for a specific protocol, follow these steps:

  1. Click Start, click Run, type regedit, and then click OK.

  2. Locate [or create] the following registry subkey:

    HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\xx.0\Common\Security\Trusted Protocols\All Applications

    Note: In this subkey, replace "xx.0" with [your version of Office; see below table§].

  3. Click the All Applications subkey.

  4. On the Edit menu, point to New, and then click Key.

  5. Type the name of the protocol that you want to exclude. For example, to disable the display of a security warning for the "Notes:" protocol, type Notes:.
    Note: Make sure that you include the colon (:) character.

  6. Press Enter.

  7. Exit Registry Editor.

Things to double check:

Your office version§

There is a different registry key for every version of office. To find your version, in any Microsoft Office Application, look under something to the tune of

File > Office Account > Click About Outlook

then look near the top to find your XX.X office version. (Note 1808 is not the version number you're looking for.)

I've got Microsoft Office 365 and here's what mine looks like:

What your office version should look like

You can also find your version using this table from Wikipedia (which I've copied the essence of below).

| Office        |  Version Number   |
|-------------  |-----------------  |
| Office 2000   |  9.0              |
| Office XP     | 10.0              |
| Office 2003   | 11.0              |
| Office 2007   | 12.0              |
| Office 2010   | 14.0              |
| Office 2013   | 15.0              |
| Office 2016   | 16.0              |
| Office 2019   | 16.0              |

In the end, my registry ended up looking like this:

Registry in finished state

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