A year ago, Microsoft said RPC over HTTP was dead from Oct 31, 2017 and that Outlook clients must use MAPI over HTTP to connect to Exchange Online. The protocol is still dead, but it will persist in a zombie-like unsupported mode. The question is for how long?
Microsoft has announced the demise of RPC over HTTP (“Outlook Anywhere”) connections, which will be blocked for connections to Exchange Online from Outlook desktop clients from October 31, 2017. The year’s notice is intended to allow tenants to upgrade clients to the necessary versions.