Much to our distress, we discovered that the contact form for the Office 365 for IT Pros website was broken. We fixed everything up and use a shared mailbox to receive the contacts logged by people on the website. In fact, we use a distribution list as the first point of contact. Its membership includes the shared mailbox and other user mailboxes. Everything works very nicely now.
You can configure Exchange Online distribution lists so that they reject messages sent to them as BCC recipients. I’m not sure how much use this feature will get, but it’s nice to have it anyway. PowerShell is the only management tool to configure distribution lists for the new block until Microsoft gets around to updating the Exchange Admin Center.