Add an Auto Reply to a Shared Mailbox in Outlook 365

To add an automatic reply to a shared mailbox, open that mailbox in Outlook on the web and go to Settings > Mail > Automatic replies, or ask an Exchange administrator to set it in the Exchange admin center. Set the reply text and dates, then choose whether to send a message to people outside your organization. Outlook for Windows does not reliably let you configure a shared mailbox’s reply from the main account’s Automatic Replies window.

What a shared mailbox auto reply does

A shared mailbox is an Exchange mailbox used by several people, often for addresses such as sales@, support@ or info@. An automatic reply sends a prepared message when someone emails it during the period you specify. It is useful for confirming that a request arrived, giving holiday hours, or directing people to another contact while a team is unavailable.

The reply belongs to the shared mailbox, not to an individual delegate’s personal mailbox. That distinction matters: setting an out-of-office message on your own account will not automatically set one on the shared address. Likewise, sending a message from the shared mailbox is different from enabling its automatic reply. The latter is an Exchange mailbox setting, even when you manage it through Outlook on the web.

Automatic replies are generally sent once to each sender while the setting is active, rather than in response to every message in a long conversation. Do not use this feature if you need a distinct answer for every email, or if replies must depend on the content of a message.

Set it up in Outlook on the web

This is a convenient option when you have permission to open the shared mailbox. Use a browser at Outlook on the web and make sure you are working in the shared mailbox itself—not your personal inbox—before changing its settings.

Sign in to Outlook on the web with your work or school account.
Select your profile picture or initials, then choose Open another mailbox. Enter the shared mailbox address and open it. If it opens in a new tab or window, continue there.
Check the mailbox name or address shown in Outlook. This helps prevent accidentally changing your personal out-of-office settings.
Select the Settings gear, choose Mail, then Automatic replies. The exact grouping can vary as Microsoft updates the web interface.
Turn on automatic replies. Enter the message for people inside your organization, and, if appropriate, enable and write a separate reply for people outside it.
If available, set a start and end time. Review the external-recipient option, save the change, and send a test message from another account.

If you cannot open the mailbox, or the Automatic replies setting is missing or unavailable, ask your Microsoft 365 administrator to configure it in Exchange. Having the mailbox appear in your Outlook folder list does not guarantee that every mailbox setting is editable from your version of Outlook.

Configure it in the Exchange admin center

An administrator can manage the setting centrally in the Exchange admin center. In the current Exchange admin center, open Recipients > Mailboxes, select the shared mailbox, open Others, and choose Manage automatic replies. The labels or layout can change, so search the mailbox details for the automatic-replies control if your tenant’s interface differs.

Choose whether replies should be sent now or for a defined period, enter the internal and external messages as needed, and save. The administrator should verify the selected mailbox address before saving; similarly named shared mailboxes are an easy source of mistakes. Access to this admin area requires an appropriate Exchange or Microsoft 365 administrative role. A regular mailbox delegate may not have it.

For a one-time change, a delegate with Full Access may be able to open the mailbox in Outlook on the web and adjust its settings, depending on the organization’s configuration. Full Access lets a user open and manage mailbox contents, but it is separate from permissions to send messages as the shared address. Automatic replies are sent by the mailbox service; a delegate does not need to compose each reply manually.

Choose the message, dates, and audience

Keep the reply useful and specific. Tell the sender what happens next, when to expect a human response, and what to do if the matter is urgent. Avoid promising a response time that the team cannot meet. For example, a support mailbox might say that a request has been received, that the team is closed on a named date, and that urgent service interruptions should be reported through a separate monitored channel.

Internal reply: Use this for colleagues who need operational context, such as the name of the person covering the queue.
External reply: Give customers a concise acknowledgement and a practical next step. Do not include confidential staffing details.
Schedule: Set a start and end time when the absence is temporary. Check the time zone and make sure the end time covers the final day you intend.
External audience: If offered a choice, decide whether to reply to all external senders or only people in the organization’s contacts. The contacts-only option may leave unfamiliar customers without an acknowledgement.

Automatic replies can disclose that an address is active. Avoid including personal travel plans, private phone numbers, sensitive customer information, or details that would create a security risk if forwarded. For a public-facing mailbox, have the relevant team approve the wording and contact details.

Outlook desktop, new Outlook, and Mac differences

In classic Outlook for Windows, File > Automatic Replies is designed around the signed-in Exchange account. If a shared mailbox is merely mounted under your own account, opening that dialog usually changes your account’s replies, not the shared mailbox’s. Do not assume that selecting the shared mailbox folder first changes which mailbox the dialog controls.

New Outlook and Outlook on the web share much of their interface, but the settings available can depend on how the shared mailbox was added and on your organization’s configuration. Open the mailbox as its own mailbox context and confirm its address before changing Automatic replies. If the control is absent, use the Exchange admin center or ask an administrator rather than experimenting with your personal account settings.

Outlook for Mac also has automatic-reply controls for an Exchange account, but the steps and available mailbox options differ by Outlook version. A shared mailbox added as an additional mailbox may not expose its own automatic-reply setting in the same way as the primary account. The reliable approach is to open the shared mailbox in Outlook on the web or have an administrator configure it in Exchange. Menu names on Mac can differ from Windows, so do not follow a Windows File > Automatic Replies path literally on a Mac.

Common problems and practical checks

If the message does not appear to send, first check that automatic replies are enabled on the shared mailbox rather than on your personal account. Then confirm that the current time falls within the configured schedule and that the recipient is covered by the internal or external audience setting. Ask the recipient to check junk mail, and allow for normal mail-delivery delays before concluding that the setting failed.

Cannot open the mailbox: Ask an administrator to confirm that you have Full Access and that the permission has had time to take effect. You may need to close and reopen Outlook or sign in again.
Cannot edit settings: Your access may allow you to read messages without managing mailbox settings, or your organization may restrict the control. Request an administrator’s help.
Reply goes to the wrong audience: Review the external-sender setting and whether the sender is treated as internal or external by your organization’s mail system.
Only one reply arrives: This is usually expected behavior, not a failure. Automatic replies are intended as an acknowledgement, not a message-per-email autoresponder.
Old wording keeps appearing: Reopen the shared mailbox’s settings and verify the saved text, schedule, and whether another rule or mail-flow process is also sending a response.

For a sensible test, send one message from an internal account and, if relevant, another from an external address. Use different test senders because the service may not send the same automatic reply repeatedly to one sender during the active period. Check both the message wording and the From address. If the shared mailbox uses a custom or secondary address, confirm that mail sent to that address reaches the mailbox whose reply you changed.

When a rule or another tool is a better fit

Automatic replies are best for a straightforward, time-limited acknowledgement. A mailbox rule may be more appropriate when the response should depend on conditions, such as a particular subject or recipient, but rules can be harder to maintain and may behave differently depending on whether they run on the server or in a client. Coordinate rule changes with the mailbox owner so that two mechanisms do not send duplicate messages.

For workflows that need per-message responses, routing, approvals, or different actions based on the email, consider a supported automation such as Power Automate or a dedicated customer-service system. These options require careful setup: poorly designed flows can create reply loops, send duplicate messages, or expose information to the wrong people. Test with controlled accounts and involve your Microsoft 365 administrator before using automation for customer communications.

Frequently Asked Questions

Can I set an automatic reply for a shared mailbox from Outlook desktop?
Sometimes a particular Outlook setup exposes the mailbox’s settings, but a shared mailbox mounted under your personal account does not reliably make File > Automatic Replies apply to that mailbox. Use Outlook on the web with the shared mailbox open, or ask an administrator to set it in Exchange.

Do I need Send As permission to set the reply?
Not necessarily. Send As and Full Access are separate permissions. Full Access or an appropriate administrator role may let you manage the mailbox, while Send As concerns messages that a user composes and sends as the shared address. Your organization’s permissions determine what you can edit.

Will the shared mailbox reply to every email?
No. Automatic replies are generally sent once per sender during the active period, so they are not a dependable way to acknowledge every message individually. Use a suitable workflow or service if each incoming email needs its own response.

Can I send different replies to coworkers and customers?
Yes, Exchange automatic replies can provide separate internal and external messages. The external option may also let an administrator limit replies to contacts. Review the available choices in your mailbox and follow your organization’s policies.

Why can’t I see Automatic replies in the shared mailbox?
You may be viewing your personal mailbox, lack sufficient access, or be using an Outlook version that does not expose the shared mailbox setting. Open the mailbox in Outlook on the web and verify its address; if the setting is still unavailable, ask an Exchange administrator to configure it.

Try it: the Date Difference Calculator: days, months, years and weekdays between two dates, with the DATEDIF formulas.

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Sources: Function behaviour and menu paths: Microsoft Support documentation for Excel. Method & sources

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