How to Use a Shared Mailbox in New Outlook

Can you use a shared mailbox in new Outlook?#

Yes. A shared mailbox in new Outlook opens, syncs and behaves much like it does in classic Outlook, and Microsoft's feature comparison lists shared mailboxes as available — both as a resource in your folder pane and as a separate account.

The part almost every guide gets wrong is that delegation is split. Microsoft's own support page states that assigning delegate permissions to mail folders in new Outlook is only partially available, and that you must use classic Outlook to assign those permissions first. Calendar delegation is different: that already works in new Outlook.

So the honest answer has two halves. Working in a mailbox someone already shared with you is fine. Being the person who grants that access is where you get pushed back to another client or to the admin centre, as of July 2026.

Using access and granting access are two different jobs#

Before you troubleshoot anything, work out which job you are actually doing. Most of the frustration in forum threads comes from someone trying to do an admin task in a mail client.

Which permission do you actually need?#

Shared mailbox problems are usually permission problems wearing a client costume. Full Access on its own lets a person read a mailbox but not send from it — Microsoft is explicit about that, and it is the single most common misconfiguration.

How to add a shared mailbox in new Outlook#

Assuming the permission already exists, this takes about a minute. If nothing appears, the problem is upstream of the client.

1. 1

   Confirm the permission exists

   An admin grants Full Access in the Microsoft 365 admin centre, plus Send As or Send on Behalf if the team needs to reply. Adding the address in Outlook does not create access, and no client-side step substitutes for it.

2. 2

   Restart new Outlook first

   Microsoft's guidance is to close and restart after being added as a member. With automapping on, the mailbox appears in the folder pane by itself and you can stop here. Permission changes take time to propagate, so do not judge it in the first two minutes.

3. 3

   Right-click your account name

   If it has not appeared, right-click your own account name in the folder pane and choose Add shared folder or mailbox. Right-clicking a folder instead of the account name gives you a different menu without that option.

4. 4

   Type the address and add it

   Enter the shared mailbox address, such as [email protected], pick it from the results and select Add. It mounts under your own mailbox in the folder pane, with its own Inbox and folders.

5. 5

   Or add it as an account instead

   New Outlook also supports shared mailboxes as accounts, which is the better option when you want notifications, rules and automatic replies for the shared address. You authenticate with your own credentials, because the shared mailbox has no password of its own.

Automapping: why it may already be there#

Automapping is why most people never run those steps. It is on by default, and when an admin grants Full Access explicitly, the mailbox is pushed into the user's profile without anyone typing an address.

Two details cause the confusion. Automapping is set on the user's mailbox rather than on the shared mailbox, and it does not work when access is granted through a security group — a common enough pattern that this alone explains many missing mailboxes.

Turning it off is an admin action, not a client setting. A user who removes the mapped mailbox will usually watch it come back, which is the moment the admin needs to disable automapping for that permission and let the user add the mailbox manually instead.

Why sent items do not save to the shared mailbox#

This is the oldest complaint in shared mailbox support, and it long predates new Outlook. Someone replies from the team address, and the message lands in their personal Sent Items where nobody else can see it.

The real cause is not the client. Microsoft documents it as default Exchange Online behaviour: messages sent from a shared mailbox are not saved to the shared mailbox's Sent Items, they are saved to the Sent Items folder of the person who sent them.

The fix is server-side. In the Microsoft 365 admin centre, open Teams and groups, then Shared mailboxes, pick the mailbox and edit the Sent items setting so copies are kept in the shared mailbox. It applies to everyone who uses it, on any client.

That is why the registry tweaks still circulating for classic Outlook are the wrong answer now. They were per-machine workarounds for a behaviour that has had a proper mailbox-level setting for years, and they do nothing at all for new Outlook, the web or mobile.

Send As vs Send on Behalf#

Send As makes the message look like the shared mailbox sent it, with no trace of the individual. Send on Behalf shows both names, in the form Jo on behalf of Support.

Most support and sales teams want Send As, because customers should see one identity. Send on Behalf suits an assistant writing for a named executive, where hiding the author would be misleading.

One practical trap: both permissions fail in the Outlook desktop client when the mailbox is hidden from the global address list. If sending breaks right after someone hides a shared mailbox from the directory, that is your answer.

Shared mailbox capability by client#

Here is the picture as of July 2026. Only the grant-permissions column differs meaningfully, and it is the column that decides whether an admin can leave classic Outlook behind.

Shared mailbox not appearing in new Outlook#

Work through these in order. Five of the six are fixed outside the client, which is the point of the whole post.

• Permission was granted through a security group, so automapping never fired. Grant it explicitly, or add the mailbox by hand.
• The change has not propagated yet. Restart new Outlook and give it time before escalating.
• The mailbox is hidden from the global address list. Microsoft notes that new members then cannot add it to their profile at all.
• Full Access exists but sending fails. Send As or Send on Behalf is missing — Full Access alone never allows sending.
• Replies vanish into a personal Sent Items folder. That is the default sent-items behaviour, fixed in the admin centre.
• You are trying to assign mail delegate access and cannot find the option. It is not there. Use classic Outlook or Outlook on the web.

If the split is a problem: the options#

We build AI Emaily, so read this section as an interested opinion and check it against our docs. It is first because shared inboxes and delegation are things we actually ship, not a bolt-on.

AI Emaily gives a team one inbox they genuinely work together: shared threads, assignment to a teammate or to the AI agent, internal comments the recipient never sees, and a clear record of who did what. Drafting runs from a Personal Context you set and client profiles you control, never from reading your old mail. Replies go through Copilot, so a person approves before anything sends, with undo and an audit trail on every action. It connects Microsoft 365, Gmail and standard IMAP, so a team on mixed providers stops being an integration project. See /docs/shared-inbox and /docs/delegation.

Be precise about what that is, though. A Microsoft 365 shared mailbox has sign-in blocked by default, so what we connect is an account you can authenticate, and the sharing and permission layer is ours rather than Exchange's. If you need Exchange-native Send As on a true shared mailbox, that is Outlook's job and we do not replace it. We ship downloadable Mac and Windows apps and a native iOS app; Android is a PWA and there is no Linux build.

Classic Outlook remains the honest answer for the granting step. Microsoft supports it via perpetual and subscription licensing until at least 2029, and message centre post MC949965 moved enterprise opt-out to 1 March 2027. That post is tenant-scoped rather than public documentation, so confirm the date in your own admin centre.

Outlook on the web is the lighter option. It can assign mail delegate permissions today, which means an admin can keep new Outlook as the daily client and open a browser tab for the occasional delegation change instead of maintaining two desktop installs.

The short version#

Using a shared mailbox in new Outlook works. Restart the client and let automapping deliver it, or right-click your account name and use Add shared folder or mailbox. Add it as an account when you want rules, notifications and automatic replies.

Granting access is the gap. Mail-folder delegate permissions still need classic Outlook or Outlook on the web; calendar delegation does not. Everything else people blame on new Outlook — missing mailboxes, failed sends, stray sent items — is a permission or a mailbox setting, and it behaved the same way in classic.