Cloud-based Message Recall in Exchange Online

m36five it doesn't require the Click 2 Run version, you can trigger a recall with any version of Outlook for Windows since 2003 so far as I know, including legacy versions of Outlook - any version of Outlook for Windows that supports the classic Recall This Message feature, which I believe is all of them since at least 2003 (unless the admin has disabled the feature through config settings like a Group Policy). However, both the sender and recipients need their mailboxes hosted in Exchange Online and within the same organization.

As noted in the FAQ we're working on an API that other email clients can use to trigger a recall. Once that's done, later this year, it'll be up to the Outlook on the Web team to decide if/when to integrate the functionality into their client. I can't speak for them, but they're very aware there is strong user interest in this functionality, so. . . .