At a glance
- A shared mailbox is a team inbox like
sales@company.com— often no extra license if under 50 GB and no direct login. - Users access it through Outlook after you grant permission.
- Do not share one person’s password — use a real shared mailbox instead.
- Send-as and Send-on-behalf are different — pick the right one.
Who this guide is for
Small businesses replacing info@ or support@ passwords taped to the wall with proper Microsoft 365 shared mailboxes.
When to use a shared mailbox
Good fit:
sales@,support@,accounts@monitored by 2–8 people- Mail only — no Teams license needed for the mailbox itself
- Read and reply from personal Outlook
Not a fit:
- Person needs their own calendar and Teams identity → use licensed user
- Mailbox over 50 GB or needs direct login → needs Exchange Online license
- Heavy Power Automate robot account → may need licensed service account
Step 1 — Create the shared mailbox
- admin.microsoft.com → Teams & groups → Shared mailboxes
- Add a mailbox → name and email address (e.g.
support@yourdomain.com) - Wait a few minutes for provisioning
Step 2 — Add members
- Open the shared mailbox → Members → Add members
- Choose licensed users who should read mail
- Save
Members restart Outlook or wait for auto-map to appear under shared folders.
Step 3 — Send mail as the shared address
Send as (appears from support@):
- Admin adds Send as permission on mailbox
- User adds “From” address in Outlook after permission propagates
Send on behalf of (shows “User on behalf of Support”):
- Different permission — use when you want transparency
Step 4 — Optional calendar
Shared mailboxes can have a shared calendar for rota or leave — useful for support teams.
Licensing rules (simplified)
| Scenario | Extra license? |
|---|---|
| Under 50 GB, no direct login, users licensed | Usually no |
| Auto-map to mobile without license | Check Microsoft current rules — mobile may require license |
| Archive or litigation hold | May need advanced licensing |
When in doubt, ask your partner before assuming “free.”
Common mistakes
| Mistake | Better approach |
|---|---|
Everyone uses support@ password | Shared mailbox + permissions |
| No one owns queue | Name a lead; use Outlook categories |
| Marketing bulk mail from shared box | Use proper bulk tool; avoid spam flags |
| Deleting leaver who “owned” mailbox | Transfer permissions first |
Summary
Create the mailbox in admin center, add members, grant Send as if needed, and train staff to use Outlook — not shared passwords. Pair with Teams channel for internal discussion.