Quick answer
A shared mailbox is a team inbox in Microsoft 365 that several people open with their own accounts — no shared password, and no licence for the mailbox itself up to 50 GB (each user still needs their own licence). To create one: Microsoft 365 admin center → Teams & groups → Shared mailboxes → Add a shared mailbox, then add members. Next, check Full Access + Send As, confirm the mailbox account's sign-in is blocked, turn on saving Sent Items in the shared mailbox, and test sending and receiving before handover.
Contents
- What is a shared mailbox, and why not just share a password?
- What to prepare, and do you need extra licences?
- 8 steps to create a shared mailbox in Microsoft 365
- Full Access vs Send As vs Send on Behalf
- How do staff add the shared mailbox in Outlook?
- From Hinet's day-to-day work
- Created it but can't open or send? How to fix it
- When should you call in an expert?
- Shared mailbox FAQ
What is a shared mailbox, and why not just share a password?
A shared mailbox is a team inbox that several people can open, read and answer, each signing in with their own account. Nobody needs the mailbox's password.
Many companies still create info@ as a normal user account and hand the password to the whole team. That causes three problems: you can't tell who replied to what, MFA is awkward to share, and every time someone leaves you have to change the password and tell everyone again. A shared mailbox fixes all three because access is tied to each person's own account.
| Option | Central inbox with shared history | Everyone uses their own account | Best for |
|---|---|---|---|
| Shared mailbox | Yes | Yes (no shared password) | Teams answering customers from info@, sales@, support@ |
| User account + shared password | Yes | No | Not recommended — no audit trail and a higher risk of compromise |
| Distribution group | No (copies go to each inbox) | Yes | Announcements and alerts that don't need a shared reply |
What to prepare, and do you need extra licences?
Prepare the name, address, and the approved list of users and permissions. The mailbox itself needs no licence up to 50 GB.
- Display name and address, e.g. Customer Service ·
info@company.com, on the right domain - A mailbox owner who approves who gets access
- Members and their permissions: open / send as / send on behalf (see permission types)
- Check the address isn't already in use by a user, group, contact or alias. If it is, don't delete the existing object just to make creation work — mail to that address could stop arriving. Find the owner first.
- An admin account with at least the Exchange Administrator role
Licensing, per Microsoft's documentation:
| Scenario | Licence needed? |
|---|---|
| Shared mailbox using up to 50 GB | None for the mailbox itself |
| Users who open the mailbox | Each needs their own licensed Exchange Online mailbox |
| More than 50 GB (up to 100 GB) | Exchange Online Plan 2 on the shared mailbox |
| In-place archive / litigation hold | Exchange Online Plan 2, or Plan 1 + Exchange Online Archiving |
8 steps to create a shared mailbox in Microsoft 365
Creating the mailbox and adding members in the Microsoft 365 admin center takes minutes; steps 5–8 are what make it work properly and securely.
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Prepare the details and check the address is free
Confirm the name, address, members and permissions with whoever has authority, then search for the address. If it's someone's alias, agree how to move it to a shared mailbox first.
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Open the Shared mailboxes page
Sign in to the Microsoft 365 admin center as an admin, check you're in the right organisation, go to Teams & groups → Shared mailboxes (select Show all if you can't see it) and choose Add a shared mailbox.
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Set the name and address
Enter the display name. Check the proposed address — both the part before @ and the domain after it (a common slip in companies with several domains) — then select Save changes and wait for it to finish.
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Add members
On the next screen choose Add members to this mailbox → Add members, pick the approved users and select Add. Reopen the mailbox to confirm the name, address and members.
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Check Full Access and Send As
Open the Exchange admin center → Recipients → Mailboxes → the mailbox → Mailbox delegation. Confirm each person has Read and manage (Full Access) and Send As as approved. Skip Send on Behalf unless you need it.
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Confirm sign-in is blocked
Go to Users → Active users, select the shared mailbox's account and make sure Sign-in is Blocked. Microsoft says to always block sign-in for shared mailbox accounts — especially ones converted from a former employee's account. Never reset the mailbox password to share with members.
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Save sent items in the shared mailbox
Back in Teams & groups → Shared mailboxes → the mailbox → Sent items → Edit, turn on Copy items sent as this mailbox (and on behalf of this mailbox if you use that permission). Replies then land in the shared Sent Items, so the whole team can see who answered what.
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Test sending and receiving before handover
Have at least two users open the mailbox in Outlook on the web and test (with a message containing nothing confidential):
- Mail from an internal account arrives; if the mailbox serves customers, test external send and receive too
- Recipients see the agreed From address
- Another member sees the reply in the shared Sent Items
- It works in the Outlook version the company actually uses
Seeing the mailbox in the admin center doesn't mean it's done — it has to send and receive.
Full Access vs Send As vs Send on Behalf
Full Access opens and manages the mailbox; Send As and Send on Behalf control sending and are granted separately. Teams replying as the shared address need Full Access + Send As.
| Permission | What it allows | Recipients see the sender as | Use when |
|---|---|---|---|
| Full Access Read and manage | Open, read, move and delete mail — but not send without a send permission | — | Everyone who needs to open the mailbox |
| Send As | Send as the shared mailbox | info@company.com | Teams replying in the company's name |
| Send on Behalf | Send on behalf of the shared mailbox | “Somchai on behalf of info@company.com” | You want recipients to see who sent it |
How do staff add the shared mailbox in Outlook?
Sign in to Outlook on the web with your own work account, right-click Folders and choose Add shared folder or mailbox. No shared password is needed.
- Sign in to Outlook on the web with your own work account and complete MFA
- Right-click Folders or your account name and choose Add shared folder or mailbox (wording may vary slightly as Microsoft updates Outlook)
- Type the shared mailbox address and confirm
- It appears in the folder list on the left, not as a new tab — expand it and open the Inbox
- When sending, show the From field and pick the shared address first
In classic Outlook, the mailbox usually appears by itself after restarting (automapping) when an admin grants Full Access to the user directly; access through a group won't automap. New Outlook may show it under Shared with me. See Microsoft's guide for details.
What Hinet checks every time before handing over a shared mailbox
These steps come from the working procedure Hinet's engineers actually use. When a client asks for a team address like info@ or sales@, we don't start by creating the mailbox — we start by getting the approved list of users and permissions, because Full Access can delete mail and shared mailboxes often hold customer data.
When users report a problem we always separate the symptoms first: can't open it means checking permissions and allowing time for them to apply; can open but can't send means checking Send As separately from Full Access. And we don't start by deleting the Outlook profile — the client is rarely the cause.
Our take: a good shared mailbox is one where you know who has access and who replied to what. Review members whenever people join or leave, watch storage before it reaches 50 GB, and plan backups if the mailbox holds important business data.
Created it but can't open or send? How to fix it
Identify the symptom, then fix that one thing. It's usually permissions or propagation time — there's no need to delete the mailbox or the Outlook profile.
| Symptom | Check | Fix |
|---|---|---|
| No Shared mailboxes menu | Right organisation, and an admin role with enough rights | Create it in Exchange admin center → Recipients → Mailboxes → Add a shared mailbox instead |
| Can't create: address already exists | Is it a user, group or alias already? | Find the owner and plan the move; don't delete the existing object straight away |
| Member added but can't open it | Does the user really have Full Access? | Allow time for permissions to apply, sign out and in, test in Outlook on the web |
| Can open but can't send | Send As granted, and From set to the shared address? | Add Send As; if just added, wait a while and retest; keep the bounce (NDR) if it still fails |
| Works on the web, not in desktop Outlook | Granted per user or via a group (automapping)? | Restart Outlook or add the mailbox manually for that version |
| Members can't see each other's replies | Is Sent items set on the shared mailbox? | Turn on Copy items sent as / on behalf and send a new test |
| Nothing sends or arrives, web or desktop | Sender, recipient, time and bounce message | Check Service health and message trace to separate mail flow from permissions |
When should you call in an expert?
If you don't have an admin account, the address clashes with an existing one, you run a hybrid setup, or fixing permissions hasn't worked, let a Microsoft 365 administrator handle it.
Deleting the wrong alias or group can stop customer email reaching you, and over-granting access risks a data leak. Hinet manages Microsoft 365 Business and IT Support Outsource for SMEs — from creating the mailbox and setting permissions to testing and sending your staff a user guide. Send us the mailbox name and user list using the form below.
Shared mailbox FAQ
Does a shared mailbox need its own licence?
Not up to 50 GB. Every user who opens it needs their own Microsoft 365 licence with an Exchange Online mailbox. For more than 50 GB (up to 100 GB), in-place archiving or litigation hold, the shared mailbox needs Exchange Online Plan 2, or Plan 1 plus Exchange Online Archiving, depending on the feature.
Can a shared mailbox replace sharing the password of an info@ account?
Yes, and it should. Everyone signs in with their own account and MFA, so you know who did what, and when someone leaves you simply remove their access instead of changing and re-sharing a password. Microsoft recommends keeping sign-in blocked for the shared mailbox account.
I added members — why can't they send as the shared mailbox?
Full Access only lets people open and read the mailbox. Sending as the mailbox needs a separate Send As permission. Check Exchange admin center > Mailbox delegation; if you've just added it, allow some time for it to take effect, and pick the shared address in the From field before sending.
Why do replies from the shared mailbox land in my own Sent Items?
That's Exchange Online's default. An admin can change it in Microsoft 365 admin center > Teams & groups > Shared mailboxes > the mailbox > Sent items by turning on Copy items sent as this mailbox (and on behalf, if used), so the whole team can see who replied.
Can people outside the company or Gmail accounts use a shared mailbox?
No. Users must be accounts in your organisation with their own Exchange Online mailbox. If someone external needs copies, use an approved forwarding rule instead of adding them as a member.
Why doesn't the shared mailbox appear automatically in desktop Outlook?
Classic Outlook shows it automatically (automapping) when Full Access is granted to the user directly; access granted through a group won't automap. Restart Outlook or add the mailbox manually. New Outlook may list it under Shared with me. Always test in Outlook on the web first to separate permission problems from client problems.
What's the difference between a shared mailbox and a distribution group?
A shared mailbox stores mail in one central inbox that everyone can open, answer and see the history of. A distribution group just forwards messages into each member's own mailbox, with no shared inbox — better for announcements. If a team answers customers together, choose a shared mailbox.
References
- Microsoft Learn — Create a shared mailbox
- Microsoft Learn — About shared mailboxes (licensing & storage)
- Microsoft Learn — Shared mailboxes in Exchange Online
- Microsoft Learn — Configure shared mailbox settings
- Microsoft Support — Open and use a shared mailbox in Outlook
Related guides
Technically reviewed by the Hinet Computer System engineering team · Last updated 12 Nov 2026