# How to Set Up a Shared Mailbox in Microsoft 365

Source: https://dijitulsupport.co.uk/guides/microsoft-365-shared-mailbox-setup/
Updated: 2026-10-10

> To set up a Microsoft 365 shared mailbox, create it in the Microsoft 365 admin centre, add members with Read and manage and Send as permissions, and it appears in their Outlook automatically. Shared mailboxes need no licence up to 50GB. dijitul support sets them up correctly for £45 an hour + VAT, or within our Complete plan.

## Key facts

- Shared mailboxes are free (no licence) up to 50GB of storage, according to Microsoft's documentation.
- A licence (Exchange Online Plan 2, or Plan 1 with Exchange Online Archiving) is needed over 50GB, for an online archive, or for litigation hold.
- Members need Read and manage (Full Access) to open it, and Send as or Send on behalf to send from it.
- With Full Access and automapping, the mailbox appears in Outlook on its own within about an hour.
- By default, emails sent as the shared mailbox are saved to the sender's own Sent Items unless you change it.
- Block direct sign-in to the shared mailbox account so nobody logs in to it with a password.

## What a shared mailbox is for

A shared mailbox is an inbox several people can read and send from, such as *info@*, *sales@*, *accounts@* or *support@*. Everyone sees the same messages, can tell what has been read and replied to, and replies go out from the shared address rather than a personal one. It has its own calendar too, useful for bookings or a shared rota.

It is better than giving several people the password to one licensed account, which breaks MFA, makes it impossible to see who did what, and costs a licence. According to Microsoft's documentation, a shared mailbox needs no licence until it goes over 50GB, needs an online archive, or is placed on litigation hold.

## Step by step: create the shared mailbox

- Sign in to the **Microsoft 365 admin centre** (admin.microsoft.com) as a global or Exchange admin.
- Go to **Teams and groups**, then **Shared mailboxes**, and click **Add a shared mailbox**.
- Enter a display name (for example "Accounts") and the email address. Choose the right domain if you have more than one.
- Click **Save changes**, then **Add members** and pick the people who need it.
- Members added here get **Read and manage** and **Send as** permissions. You can fine-tune these later in the Exchange admin centre under Recipients, then Mailboxes, by selecting the mailbox and opening Delegation.

If you are converting an existing user mailbox (for example a leaver's) into a shared one, use **Convert to shared mailbox** in the Exchange admin centre, then remove the licence once the conversion has finished. Check the mailbox is under 50GB first.

## Getting it into Outlook

- **Outlook for Windows (classic):** with Full Access and automapping on, the mailbox appears in the folder list by itself, usually within an hour. Restart Outlook if it does not.
- **New Outlook and Outlook on the web:** right-click *Folders* or *Shared with me*, choose **Add shared folder or mailbox**, and type the address.
- **Phones:** the Outlook app for iOS and Android supports shared mailboxes. Tap the account icon, then add a shared mailbox.
- **Sending:** in a new message, show the **From** field and choose the shared address. If Outlook says you do not have permission, the Send as permission has not applied yet; it can take up to an hour.

## Settings worth changing

- **Sent items.** By default, a message sent as the shared mailbox is saved only in the sender's own Sent Items, so colleagues cannot see what was sent. An admin can change this with PowerShell: *Set-Mailbox accounts@yourdomain.co.uk -MessageCopyForSentAsEnabled $true -MessageCopyForSendOnBehalfEnabled $true*.
- **Block sign-in.** A shared mailbox has an underlying user account. In the admin centre, open it under Users and choose Block sign-in so nobody can log in to it directly.
- **Automapping.** If someone has access to lots of shared mailboxes and Outlook gets slow, remove and re-add their permission with automapping off, then add the mailbox manually.
- **Signatures.** Set a shared signature for the address so replies look consistent.
- **Too big?** Watch the size. Past 50GB, the mailbox needs a licence.

## Common problems

- **Mailbox not showing in Outlook**: permissions take time to apply, or automapping was turned off. Add it manually or wait an hour and restart Outlook.
- **"You do not have permission to send"**: the user has Full Access but not Send as.
- **Emails in the shared inbox not syncing**: in classic Outlook, check *Download shared folders* in the cached mode settings, or the OST file may need rebuilding.
- **Search not finding messages**: classic Outlook searches shared mailboxes differently; try Outlook on the web to confirm the email is there.

## When to call dijitul support

We set up shared mailboxes, permissions, sent item behaviour and signatures, convert leavers' mailboxes so you stop paying for their licence, and fix Outlook when a shared mailbox will not appear or send. One-off work is £45 an hour + VAT. The **Complete plan at £99 a month + VAT** includes Microsoft 365 helpdesk support for your team. See Microsoft 365 support and Outlook support.

## FAQs

### Does a Microsoft 365 shared mailbox need a licence?

Not usually. Microsoft's documentation says a shared mailbox is free up to 50GB. It needs a licence, such as Exchange Online Plan 2, if it goes over 50GB, needs an online archive, or is placed on litigation hold.

### Why can I see the shared mailbox but not send from it?

You have Read and manage (Full Access) but not Send as or Send on behalf permission. An admin can add it in the Exchange admin centre under the mailbox's delegation settings. It can take up to an hour to apply.

### How do I make sent emails appear in the shared mailbox?

An admin runs the Set-Mailbox PowerShell command with MessageCopyForSentAsEnabled and MessageCopyForSendOnBehalfEnabled set to true for that mailbox. After that, copies of messages sent from it are also saved in the shared mailbox's own Sent Items.

### Can I convert a leaver's mailbox into a shared mailbox?

Yes. Convert it in the Exchange admin centre, give the right people access, then remove the licence. The mailbox must be under 50GB to stay unlicensed. This keeps the old emails without paying for a user licence.

### Can dijitul set up shared mailboxes for us?

Yes. dijitul creates shared mailboxes, sets permissions, fixes sent items and signatures, and sorts Outlook issues for UK businesses. One-off work is £45 an hour + VAT, or it is covered by the £99 a month + VAT Complete plan's helpdesk.

## Pricing and contact

Support plans from £25 a month + VAT, or £45 an hour + VAT for one-off fixes. Plans: Essential £25/month + VAT (Website software updates (core, plugins, themes) applied and checked, Daily backups, Uptime monitoring, Security monitoring); Business £50/month + VAT (Everything in Essential, 1 hour of fixes or changes every month, Priority support); Complete £99/month + VAT (Everything in Business, 3 hours of fixes or changes every month, IT and Microsoft 365 helpdesk for your team). Ad-hoc support is £45 an hour + VAT. The first 30 minutes are the minimum charge, then we bill in 15-minute blocks. Contact: 01623 650333, support@dijitul.uk, https://dijitulsupport.co.uk/contact/