Description
Shared mailboxes are considered unique mailboxes in both Microsoft and Shield. As such, mail sent to shared mailboxes is subject to different actions than mail sent to licensed user mailboxes. Those differences are outlined below.
Shared Mailboxes Defined
Shield shared mailboxes are the same as Microsoft 365 shared mailboxes, so the definition is identical: A shared mailbox is a mailbox that multiple users can use to read and send email messages.
How Shared Mailboxes are Added to Shield
Shield shared mailboxes are added to Shield with the mailbox type of Shared. By default, preferences for shared mailboxes are set as follows:
- New Sender Banner: Disabled
- Heads Up Display (HUD): Disabled
- Protection Level: Minimum - Only high risk level messages are filtered
Because a shared mailbox in Microsoft 365 does not have a password, users cannot sign in to Shield to change its preferences. Shield Admins must make any preference changes to the Shared mailbox in Shield.
The Trust Network is not applied to shared mailboxes. Even if a trust decision is chosen for a sender, Shield will disregard it and pay attention to only the risk levels of a message. Messages will follow this pattern of assessed risk:
- * High: emails are held in Shield's Jail, outside the mailbox.
- Moderate: emails are sent to the Junk folder.
- ** Low: emails are sent to the Junk folder.
- None: emails are delivered to the Inbox.
* By default, a shared mailbox is configured to Minimum protection which monitors only High Risk messages. If it's set to Maximum protection, only a Shield Admin can manage risk-level activities, which can lead to significant administrative overhead.
** Note that Low Risk behavior differs from that of a licensed user account, as trust network decisions are factored into deliverability of low-risk messages to licensed users.
Protection Levels, Risk Levels, and Shared Mailbox Delivery
With the minimum security protection level, moving a risk setting to high risk will result in less mail being delivered to the shared mailbox. This is the default setting.
With the maximum security protection level, moving a risk setting to none will result in more mail being delivered to the shared mailbox. Maximum security protection is not the default setting, but a Shield Admin can update the shared mailbox to maximum security if needed.
Only Shield Admins can view Spotlight for a shared mailbox and take any action on a Jailed message.
Getting Help
If you need assistance with shared mailbox delivery within Shield, please contact the Partner Success team.
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