Jelly doesn't directly integrate with Office365 or any existing shared mailboxes, at least not at the moment. You just forward email into it, from any source, and then use the Jelly web application to collaborate on those emails.

In the future we'll be looking at ways to streamline the setup with existing mail providers like Google, Office365 and so on, but we're starting out simple. There are lots of teams sharing logins to single email accounts whose lives we want to improve.