Until Now?

"These efforts, though, have failed to gain mass market share and left Outlook firmly entrenched as the default email client for business and looking unassailable - until now."

Umm... I disagree Everyone is still firmly entrenched, and as the half-way one way opening of the spec progresses, I imaging they at least think they will be able to more firmly entrench everyone.

This is bad and no-one should bite the poison bait. You can read from Outlook, but not write too outlook. This means you would still need outlook.

Everyone should avoid like the plague until the "promised" write capability is delivered.

Soon could be 30 years in Microsofts head.