Shared mailboxes in Microsoft 365

How to create and use a shared mailbox in Microsoft 365 — perfect for team inboxes like info@, support@, or hello@yourcompany.com.

A shared mailbox is an email inbox that multiple people can access and send from. It's perfect for addresses like info@yourcompany.com, support@yourcompany.com, or hello@yourcompany.com — where the whole team needs to see and respond to messages.

Quick summary

Shared mailboxes in Microsoft 365 don't need their own license (up to 50 GB). Multiple people can read and reply from the same address. You create them in the admin center under Teams and groups → Shared mailboxes, then add the people who should have access. The mailbox then shows up inside their own Outlook after they restart it.

How shared mailboxes work

A shared mailbox is like a regular email inbox, but:

No one logs in directly — team members access it through their own Outlook accounts. Microsoft's guidance is that sign-in should stay blocked on the mailbox's own account, and every new shared mailbox has sign-in blocked by default.
Multiple people can work in it — everyone with access can read the messages, and replies go out from the shared address rather than the individual's. Sending from the shared address is a separate permission, though: see "Reading isn't the same as sending" below.
A shared calendar comes with it — creating the mailbox creates the calendar.
Sent replies are not shared by default — a message sent from the shared mailbox lands in the sender's Sent Items, not the shared mailbox's. An admin can change that (see below), and on a team inbox it's usually worth doing.
No license needed — a shared mailbox can store up to 50 GB of data without one. Each person who uses it does need their own licensed mailbox, though.
It's for your own team only — you can't give someone outside your business, such as a person with a Gmail account, access to a shared mailbox.
It tops out at 25 people — Microsoft supports a maximum of 25 users on one shared mailbox. Past that, people may see connection failures or duplicated messages, and a Microsoft 365 group is the better tool.

Creating a shared mailbox (admin)

Admin access required

Sign in to the admin center at admin.microsoft.com with an account that has the Exchange admin role.

Go to Teams and groups → Shared mailboxes in the left-hand menu. If you don't see it, select Show all at the bottom of the navigation first.

Select + Add a shared mailbox.

Enter a name for the mailbox — "Support", say. That choice sets the email address, and you can edit the address if you want something different, such as support@yourcompany.com.

Select Save changes. The mailbox is created, though it can take a few minutes before you can add members.

Under Next steps, select Add members to this mailbox, then Add members. Search for the people who should have access, select Add, and close.

Ready to use

If automapping is on in your business — it is for most people — the shared mailbox appears in each member's Outlook app on its own, once they close and restart Outlook. In Outlook on the web they add it themselves: right-click Folders in the left pane and choose Add shared folder or mailbox.

Accessing the shared mailbox in Outlook

Once you've been added to a shared mailbox, close and restart Outlook and it should appear in your folder pane. In new Outlook, look for a Shared with me folder — expand it and the shared mailbox sits underneath, with its own Inbox, Drafts, and Sent Items.

In Outlook on the web, add it yourself: right-click Folders in the left pane, choose Add shared folder or mailbox, and type the address (for example info@yourcompany.com). It then appears in your folder list, and you can select it just like your own inbox.

Sending from the shared mailbox

Choose New mail. At the top of the message, select More actions and then Show From. The first time you send from the shared mailbox, right-click the From address, choose Remove, and type the shared address instead. From then on it's an option in the From dropdown, and your recipients only ever see the shared address.

Reading isn't the same as sending

Access to a shared mailbox comes in parts: Full Access lets someone open the mailbox and work in it, but Microsoft is clear that it does not let them send from it — that takes Send As or Send on Behalf permission as well. If a colleague can read the mailbox but gets a permissions error when they try to reply, that's the missing piece, and an admin can grant it from the Exchange admin center under Recipients → Mailboxes → the mailbox → Manage mailbox delegation.

Managing the shared mailbox

As an admin, go back to Teams and groups → Shared mailboxes and select the mailbox. From there you can:

Add or remove members, and change what each of them can do.
Set up an automatic reply — select Edit under Automatic replies. Text only; images aren't supported here.
Share the Sent Items — select Edit under Sent items, so replies sent from the mailbox are saved in the mailbox rather than only in the sender's own Sent Items.
Forward everything elsewhere — select Edit under Email forwarding. You don't need a licence on the mailbox to forward, and to reach several addresses you point the forward at a distribution group.
Rename it or change its address — under Basic information and Email addresses.
Convert a departing user's mailbox to a shared mailbox, which preserves their email without a paid licence. See Removing a user safely — and note that once a mailbox has been converted, the account behind it has to stay.

Shared mailboxes over 50 GB need a license

Shared mailboxes are limited to 50 GB. To raise that to 100 GB, the mailbox has to be assigned an Exchange Online Plan 2 licence. Watch the size, because Microsoft's description of hitting the ceiling is unpleasant: for a while you can still receive but not send, and after that the mailbox stops receiving and senders get a non-delivery receipt.

Common questions

The shared mailbox isn't appearing in Outlook. What do I do?

If you were only just added, it can take a few minutes. Wait a little, then close and restart Outlook again — that restart is what makes it appear. If it still doesn't show up, ask the admin to confirm you're on the mailbox's member list, or add it by hand: in new Outlook, right-click your account name in the folder pane and choose Add shared folder or mailbox.

Can I get notifications for new messages in the shared mailbox?

Not by default. In new Outlook, adding the shared mailbox as an account (rather than just opening it under Shared with me) is what turns on notifications, along with things like the unread count, automatic replies, rules, and Focused Inbox for that mailbox. In Outlook on the web, you have to open the shared mailbox in its own browser window: select your name on the navigation bar, choose Open another mailbox, and type the address.

Can the shared mailbox have its own calendar?

Yes — creating a shared mailbox creates a shared calendar with it, and Microsoft recommends using that rather than a SharePoint calendar for tracking appointments and where people are. Reach it through Outlook's calendar view and select the shared mailbox. Any member can create, view, and manage appointments on it, and everyone else sees the changes.

What's the difference between a shared mailbox and a distribution group?

A shared mailbox is a real inbox — you can read, reply, and organize messages there. A distribution group (or list) just forwards email to its members' individual inboxes; there is no shared inbox. Use a shared mailbox when a team needs to manage replies together. Use a distribution group when you just need to reach multiple people at once.

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