Applies To: Microsoft 365 Exchange Online (not third-party Hosted Exchange platforms)

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Overview

In Microsoft 365 Exchange Online, you can create a single Shared Mailbox that handles multiple departmental addresses (for example sales@, support@, billing@, and info@).

Using Mail Flow Rules, you can configure Microsoft 365 to send automatic replies that are unique to each alias - all while managing everything from one shared inbox and without purchasing additional licenses.

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How It Works

• A Shared Mailbox allows multiple people to access and manage the same inbox.

• You can assign several aliases (alternate addresses) to that shared mailbox, such as:

– sales@domain.com

– support@domain.com

– billing@domain.com

All incoming messages to those aliases deliver into the same shared mailbox.
This method keeps things simple - one inbox, no extra license cost, and the flexibility of multiple “faces” for your company.

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Setting Up Automatic Replies per Alias

While Microsoft 365 doesn’t automatically display which alias received a message, you can create a Mail Flow Rule (also called a Transport Rule) to detect which alias was contacted and send a customized auto-reply message for that address.

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Step-by-Step Configuration

1. Create the Shared Mailbox

– Go to the Microsoft 365 Admin Center and select Teams & Groups → Shared Mailboxes.

– Create a new shared mailbox (for example info@domain.com).

– Add any users who should have access.

2. Add Aliases

– Open the mailbox’s properties.

– Add additional addresses such as sales@domain.com and support@domain.com.

– All messages sent to these aliases will deliver to the shared mailbox.

3. Create Mail Flow Rules

– Open the Exchange Admin Center (EAC).

– Navigate to Mail Flow → Rules.

– Click Add (+) and choose Create a new rule.

– Give the rule a descriptive name, such as “Auto-Reply for sales@domain.com.”

– Under Apply this rule if…, choose The recipient is and select the alias sales@domain.com.

– Under Do the following…, select Reply with message and enter your desired auto-reply (for example, “Thank you for contacting our Sales Department! We’ll respond as soon as possible.”).

– Save the rule.

4. Repeat for Each Alias

– Create a similar rule for support@domain.com, billing@domain.com, etc., each with its own message.

5. Test the Configuration

– Send a test email to each alias to verify the correct reply message is triggered.

– Replies will always come from the shared mailbox’s primary address, not the alias, but the sender will still receive the correct message.

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Advantages of This Method

• No paid license is required for the shared mailbox.

• Centralized message management and retention.

• Custom automatic replies per department or alias.

• Easy for team members to access from Outlook or the web.

This approach provides the flexibility of multiple departmental addresses without the overhead of managing separate accounts.