One long standing feature of how Microsoft Exchange works has recently changed: where “Sent Items” reside when you “Send As” another recipient. The traditional flow is that if “User A” has privileges to “Send As” “User B”, then the message would go in the “Sent Items” folder of “User A”. This changed with Exchange Server 2013 CU9 and Exchange Online with the following: Want more control over Sent Items when using shared mailboxes. Fortunately, this feature is disabled by default and things work the same as the original method, and I will explain why this is a good thing below.

So here is the issue: shared mailboxes do not require a license. The rationale from Microsoft is that you license users and a shared mailbox can only be accessed by a licensed user via their own user mailbox. This is great for customers because they can create these shared mailboxes and allow groups of users to share the mailbox and respond to messages. However, since it isn’t licensed, the mailbox lacks many features: Online Archive, Retention Policies, and In-Place/Legal Holds.

So, this causes two issues:

1) There are no backups in Exchange Online and the easy way to manage this is to use the underlying resiliency of Exchange Native Data Protection and implement Online Archive (with unlimited space in Exchange 2016, assuming you have the storage to support this, and Exchange Online), Retention Policies to move messages to the Online Archive, and In-Place/Legal Hold to make the messages immutable. This means that if a user deletes a message, it ages out of the Deleted Items Retention, and you implement In-Place/Legal Hold for 6 months, 1 year, indefinitely, you can use eDiscovery to find the messages and recover them for the user. This is a great value when you are already paying for Office 365 and you can eliminate a significant cost related to backups… which can be rather significant just considering email.

2) You have a regulatory or business policy that requires you to retain messages for some period time for legal purposes. You utilize these same features to defend or litigate.

Now, let’s say you enable the new Sent Items behavior and you fall under one of these scenarios. And because Shared mailboxes don’t require licenses and customers don’t tend to want to pay for an “unnecessary” license, these messages will not be retained; they are in the “Sent Items” of the Shared mailbox without the capability to have a hold.

This is something that I routinely advocate. Buy an Exchange Online Plan 2 license for your Shared mailboxes. It is $8/mailbox/month, significantly cheaper than than buying an Office 365 E3 license listed at $22/user/month. The Office 365 E3 license includes Exchange Online Plan 2, so it is the same feature set from an Exchange perspective and a Shared mailbox doesn’t need SharePoint, Skype for Business, or Office 365 ProPlus. This is my minimum recommendation for ALL licensing with Exchange Online if you have any of the above requirements, because Office 365 E1 or less (like kiosk licensing) do not cover you.

Perhaps Microsoft will respond to this gap by allowing for In-Place/Legal Hold for Shared mailboxes based on the number of licenses you hold. We can hope.