Register protocol handlers

Set this policy (recommended only) to register a list of protocol handlers. This list is merged with ones registered by the user and both are available to use.

To register a protocol handler:

- Set the protocol property to the scheme (for example, "mailto")
- Set the URL property to the URL property of the application that handlers the scheme specified in the "protocol" field. The pattern can include a "%s" placeholder, which the handled URL replaces.

Users can't remove a protocol handler registered by this policy. However, they can install a new default protocol handler to override the existing protocol handlers.

In the examples in this section, the URL points to the Outlook on the Web (OWA) endpoint used in Exchange Online. If you're targeting Exchange Server (on-premises), use the following URL and replace mail.contoso.com with your organization's OWA endpoint:

https://mail.contoso.com/?path=/mail/action/compose&mailtouri=%s

Example value:

[
{
"default": true,
"protocol": "mailto",
"url": "https://outlook.office.com/mail/deeplink/compose?to=%s"
}
]