I have developed a custom protocol handler (let's call it "foo://") for use on my system by registering an executable at
HKEY_CLASSES_ROOT\foo\shell\open\command. So far, so good.
I would like to send and receive links that use the foo:// protocol in emails. However, when I try to open one of these links in Outlook, I get the "This location may be unsafe" message below. I could just click "Yes" every time, but I would rather stop the message from appearing in the first place.
I've found instructions for how to disable the warning altogether (e.g. here - Add a DWORD value "DisableHyperlinkWarning" = 1 to
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\...\Common), but that's not what I'm after. Rather, I'd like to disable the warning on a per-protocol basis, so that my "foo://" protocol is whitelisted, but other protocols still show this warning when appropriate.
Can I do that? I'm using Outlook 2013.