A shared mailbox is the cleanest way to handle a team address like info@, support@, or sales@ without paying for an extra user account or sharing one person’s password. Several people open the same mailbox, read what lands there, and reply from the shared address. Nothing is tied to a single user, so when someone leaves the team you just remove their access instead of untangling a personal account.
There are two places you can create one: the Microsoft 365 admin center, which is quick and fine for most cases, and the Exchange admin center (EAC), which gives you finer control over permissions and delegation. This walkthrough covers both, explains the permission types that trip people up, and clears up the license question that comes up on almost every ticket.
Before you start
A few things are worth confirming up front so you don’t create a mailbox and then fight with permissions later.
Before you create the shared mailbox
- You have Exchange Administrator or Global Administrator rights
- You've agreed the address (e.g. [email protected]) and a clear display name
- You know which users need access and what they need to do (read only vs send)
- The domain you want to use is already verified in the tenant
- You understand the 50 GB license-free limit (covered below)
Option 1: Create it in the Microsoft 365 admin center
This is the fastest route and the one to use unless you have a specific reason to go deeper.
- Sign in to the Microsoft 365 admin center (
admin.microsoft.com). - Go to Teams & groups → Shared mailboxes (older tenants list it under Groups → Shared mailboxes).
- Click Add a shared mailbox.
- Enter a Name (the display name users will see) and the email address, then pick the verified domain.
- Click Save changes. The mailbox is created in a minute or two.
- On the next screen, choose Add members to this mailbox to grant access right away, or come back to permissions later.
That’s the whole creation step. The part people get wrong is the permissions, so it’s worth slowing down there.
Option 2: Create it in the Exchange admin center
The EAC (admin.exchange.microsoft.com) is the better choice when you want to set Full Access,
Send As, and Send on Behalf separately, or manage automapping behaviour.
- In the EAC, go to Recipients → Mailboxes.
- Click Add a shared mailbox.
- Fill in the display name and email address, pick the domain, and save.
- Open the new mailbox, go to the Delegation tab, and add users under Read and manage (Full Access), Send as, and Send on behalf as needed.
If you prefer PowerShell — handy when you’re creating several mailboxes or scripting onboarding — the cmdlets are straightforward:
# Connect first (ExchangeOnlineManagement module)
Connect-ExchangeOnline
# Create the shared mailbox
New-Mailbox -Shared -Name "Support" -DisplayName "Support Team" -Alias support `
-PrimarySmtpAddress [email protected]
# Grant Full Access (auto-mapping on by default)
Add-MailboxPermission -Identity [email protected] `
-User [email protected] -AccessRights FullAccess -InheritanceType All
# Grant Send As
Add-RecipientPermission -Identity [email protected] `
-Trustee [email protected] -AccessRights SendAs -Confirm:$falseUnderstanding the three permission types
This is where most shared mailbox problems start. The three permissions do different things, and granting the wrong one is why users complain that they “can see the mailbox but can’t send from it.”
Shared mailbox permissions, plain English
| Full Access (Read and manage) | Open the mailbox, read, move, and delete items. Does NOT let you send as the mailbox by itself. |
|---|---|
| Send As | Send mail that looks like it came directly from the shared address. The recipient sees only the shared mailbox. |
| Send on Behalf | Send mail shown as 'You on behalf of Support Team'. The recipient sees who actually sent it. |
For a typical support or info mailbox, grant Full Access + Send As. That lets the team open the mailbox and reply so the message comes from the shared address cleanly. Use Send on Behalf only when you specifically want recipients to see which individual responded.
Outlook auto-mapping: when the mailbox shows up on its own
When you grant Full Access through the standard method, Exchange Online turns on auto-mapping. Outlook then adds the shared mailbox automatically the next time it connects, with no manual setup. The mailbox appears in the folder list under the user’s own mailbox.
A few realities to know:
- Auto-mapping isn’t instant. It can take anywhere from a few minutes to an hour, and the user often has to restart Outlook before it appears.
- It only works for Full Access. Send As and Send on Behalf don’t add the mailbox to Outlook — they only affect sending.
- If you grant Full Access with auto-mapping turned off, the user has to add the mailbox manually under File → Account Settings → Change → More Settings → Advanced → Add.
To turn auto-mapping off deliberately (useful for very large mailboxes that slow Outlook down):
Add-MailboxPermission -Identity [email protected] `
-User [email protected] -AccessRights FullAccess `
-InheritanceType All -AutoMapping:$falseThe license question: when is a shared mailbox free?
This is the detail that saves money and the one people most often get wrong. A shared mailbox does not need its own Microsoft 365 license for normal use, up to 50 GB of storage. Below that limit, you create it, grant access to licensed users, and pay nothing extra for the mailbox itself.
You need to assign a license to the shared mailbox when:
- It grows beyond 50 GB. At that point Exchange Online requires a license to keep delivering mail to it.
- You want to enable an online archive for the shared mailbox.
- You apply litigation hold or certain retention features that depend on a license.
Shared mailbox licensing at a glance
| Storage under 50 GB | No license needed for the mailbox |
|---|---|
| Storage over 50 GB | License required (e.g. an Exchange Online plan) |
| Enable archive mailbox | License required |
| Litigation hold / some retention | License required |
| Users who open the mailbox | Each needs their own licensed account regardless |
Quick verification
After you create the mailbox and set permissions, confirm it actually works before you tell the team it’s ready:
- Have one member open Outlook and confirm the mailbox appears (or add it manually).
- Send a test message to the shared address from an outside account and confirm it lands.
- Reply from the shared mailbox, picking the shared address in From, and confirm the recipient sees the shared address (not the individual’s).
- Check the Sent Items — replies sent with Send As are stored in the shared mailbox’s Sent Items so the whole team can see the history.
If users hit repeated sign-in prompts when the mailbox is added, that’s usually an Outlook credential issue rather than a permissions problem — our guide on fixing Outlook’s endless password prompt walks through the cached-credential and modern-auth fixes. And if mail isn’t arriving at the shared address at all, work through Microsoft 365 email not sending or receiving to check mail flow and DNS.
Wrapping up
Creating a shared mailbox is quick; getting the permissions and licensing right is what makes it work day to day. Create it in the admin center for speed or the Exchange admin center for control, grant Full Access + Send As for a normal team mailbox, and lean on auto-mapping so Outlook picks it up without manual setup. Keep it under 50 GB and it stays license-free — just remember every person who opens it still needs their own licensed account.
If you’re standing up several team addresses at once, the PowerShell approach pays off fast, and it gives you a repeatable script you can reuse during onboarding.
