Custom URI-Handler: Outlook-Integration?

Question

For our Application, we have a custom uri handler, which allows to open some views inside the application from external sources (i.e. app://viewProduct/225545568)

This is working fine, hower when such a link is pasted inside an Email, Outlook does not turn it into a "clickable" link.

• We registered the URI-Handler under HKEY_CURRENT_USER\Software\Classes\app, so calling it from WIN + R brings up the application perfectly fine.

Is there a way, that Outlook can understand (registered) URIs to turn them into HyperLinksautomatically? (Or would we need to deploy some sort of firmwide macro to make this happen?)

Answer 1

Heres a workaround that worked out perfectly fine:

I'm still searching for a proper solution, just wanted to leave this woraround "here" already.

After some research, I found out that Outlook by default links a certain amount of "protocols" (Hardcoded): So I attempted to register "my" application with the mms-protocol, which we don't need inside a Business-Environment.

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Deleted first try, as only applicable for Windows 7

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So I played around a little more and figured out, that the following keys are required for Windows 7 and Windows 10 to get things rolling.

Note: For Windows 10, this will only "enroll" your application as a suitable default application for the protocol. You have to manually assign the application, using "Windows 10's Default App -> By Protocol"-Menu. (As long as this applies for Chrome - so Google-Devs don't have a workaround - I don't spend any minute on this :P )

The Good News: Setting all the keys on any system doesn't seem to cause any problem. (So let's ignore that little bit of registry polution :-) )

Use on your own risk - my tests are positve in a very narrow minded environment.

Replace Config.MyApplicationURLHandler with your executable, i.e. C:\Path\To\Executable %1 Replace MyApplication with your application name.

private void RegisterMyProtocol()
{
     //Step 1: Register for the MMS-Protocol. 
    //Thats some media plaer stuff, we don't need at all. 
    //We use this, because it will be autolinked in Outlook / word / excel. 
    RegistryKey key = CreateRegistryChain(Registry.CurrentUser, "Software/CLASSES/mms");
    key.SetValue(string.Empty, "URL:mms Protocol");
    key.SetValue("URL Protocol", string.Empty);
    key.Close();

    key = CreateRegistryChain(Registry.CurrentUser, "Software/CLASSES/mms/shell/open/command");
    key.SetValue(string.Empty, Config.MyApplicationURLHandler);
    key.Close();

    //Step 2: Create required entries for windows 10. 
    //NOTE: Win 10 Users need to select Uri-Schemes manually.
    key = CreateRegistryChain(Registry.CurrentUser, "Software/CLASSES/mms/shell/open/command");
    key.SetValue(string.Empty, Config.MyApplicationURLHandler);
    key.Close();

    key = CreateRegistryChain(Registry.CurrentUser, "Software/MyApplication/Capabilities");
    key.SetValue("ApplicationDescription", "MyApplication");
    key.SetValue("ApplicationName", "MyApplication");
    key.Close();

    key = CreateRegistryChain(Registry.CurrentUser, "Software/MyApplication/Capabilities/URLAssociations");
    key.SetValue("mms", "mms");
    key.Close();

    key = CreateRegistryChain(Registry.CurrentUser, "SOFTWARE/RegisteredApplications");
    key.SetValue("MyApplication", "Software\\MyApplication\\Capabilities");
    key.Close();

    //Step 3: Remove the original UrlAssociation. 
    key = CreateRegistryChain(Registry.CurrentUser, "SOFTWARE/Microsoft/Windows/Shell/Associations/UrlAssociations");
    if (key.GetSubKeyNames().Contains("mms"))
    {
        key.DeleteSubKey("mms");
    }
    key.Close();
}

private RegistryKey CreateRegistryChain(RegistryKey root, String keyChain){
    String[] keys = keyChain.Split('/');

    foreach(String key in keys)
    {
        if (!root.GetSubKeyNames().Contains(key))
        {
            root.CreateSubKey(key, true);
        }

        root = root.OpenSubKey(key, true);
    }

    return root;
}

Note: By default the mms-Protocol causes Outlook to display a security warning. So either add the Protocol to your trusted Protocols through the GPO, or by using the registry key:

(Where the version 16.0 needs to match your Outlook version)

HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Common\Security\Trusted Protocols\All Applications\mms:

If some keys don't exist just Create them.

Don't forget to sanitize inputs within your application, as we don't want to handle the real stuff which uses the mms-protocol. :-)