Shared mailboxes explained
Shared mailboxes are mailboxes multiple people can monitor. Here's how they differ from groups, distribution lists, and personal mailboxes.
A shared mailbox is a mailbox in Exchange Online that several people can read and send from, without needing a licence per person. They're how addresses like support@, sales@, or info@ get handled by a team rather than an individual.
What a shared mailbox is
A shared mailbox:
- Has its own primary SMTP address.
- Doesn't require a Microsoft 365 licence (up to 50 GB; beyond that, it does).
- Can't be signed into directly — there's no password.
- Is accessed by delegated users who have Full Access and/or Send As / Send on Behalf permissions.
- Shows up in Outlook automatically for those users via auto-mapping.
For each delegated user, the shared mailbox appears as a separate folder under their mailbox tree in Outlook, OWA, and the mobile app.
What it's good for
- Generic team addresses: support, sales, info, hr, careers.
- Ticketing queues that don't yet have a ticketing system.
- Functional roles that change owner over time without disrupting the address.
Shared mailboxes vs Microsoft 365 Groups
A Microsoft 365 Group is much more than an email address — it also has a SharePoint site, a OneNote, a Planner plan, and can be the basis of a Teams team. Mail to a group can land in members' inboxes or in the group's own conversation history.
If the team wants a shared workspace alongside the inbox, a group is usually the better choice. If they just need a shared address to monitor and reply from, a shared mailbox is simpler.
Shared mailboxes vs distribution lists
A distribution list (or distribution group) is a fan-out address: mail sent to it is delivered to each member's personal inbox. There's no shared storage. Compared to a shared mailbox, this means no collaborative read/reply, but everyone gets their own copy. Use it for announcements, not for shared queues.
Operational tips
- Set delegated users to send on behalf or send as depending on whether you want the original sender's name to appear.
- Use Sent Items copy settings (an option in Exchange) so sent mail lands in the shared mailbox's Sent folder, not the sender's personal one.
- Apply Purview retention to shared mailboxes the same way you do to personal ones.
- For high-volume scenarios, route the address into a real ticketing system (Zendesk, ServiceNow, Dynamics) instead of letting it grow.
Shared mailboxes are a great low-cost starting point for team-based email. They're a stop-gap for serious workflow, not a destination.