Edit 6/15/2015:
We are starting to make this feature available again in Office 365. Note that the new shared mailbox Sent Items behavior is disabled by default. If you want to enable it for your us...
Updated Jul 01, 2019
Version 2.0
Blog Post
@Nino Bilic "@verypsb: there is no change in how Deleted Items work here; majority of our customers told us about needs around sent Items and that is what we have addressed with this particular feature."
Are you kidding me?? What's the point of a collaborative email box if deleted or sent items are being stored in the user's personal mailbox?? The logic of this "functionality" is completely stupid. We've been using the work-around registry settings to store
Shared Mailbox items (in cached mode) in the PROPER place for years now because of this. And there are TONS of problems using cached mode for Shared Mailboxes. Please fix the deleted issue as well, ASAP. And please don't use the excuse that your customer's
haven't asked for it. There's no legitimate way for your customers to talk to the developers, only low level support technicians.