Summary

This guide helps you troubleshoot and resolve: Microsoft 365 Shared Mailboxes vs Distribution Lists: Which One Should Your Brisbane Business Use?. Follow the steps below to fix the issue.

Common Causes

Small businesses moving away from shared login details and legacy cPanel webmail often need a central email address for customer enquiries, such as sales@ or accounts@. Microsoft 365 offers two common options: shared mailboxes and distribution lists. While they can look similar from an inbox, they serve different purposes. Choosing the wrong one can lead to missed replies, duplicated messages, or emails landing in client junk folders. This guide explains the differences and helps Brisbane businesses decide which setup fits their needs.

Shared Mailboxes vs Distribution Lists

A shared mailbox is a separate mailbox that multiple users can access using their own Microsoft 365 credentials. Emails sent to sales@ or info@ are stored in one central location, and team members can read, reply to, and organise messages without sharing passwords. A shared mailbox also includes its own calendar and contact list, making it useful for teams that need to coordinate appointments or track customer interactions.

A distribution list (or distribution group) is an email address that forwards messages to the inboxes of its members. When someone sends an email to the list, each recipient receives a copy in their personal mailbox. Replies come from the individual user's own email address, not from the distribution address. Distribution lists are best for internal notifications rather than managing customer enquiries.

Key Differences

• Shared mailbox: Central inbox, sent items stored together, shared calendar, replies from the shared address, no additional licence required for the mailbox itself (users need their own licences).
• Distribution list: Copies delivered to member inboxes, no central storage, replies from individual addresses, simple to set up for one-way announcements.

When to Use a Shared Mailbox

Use a shared mailbox when your team needs to manage incoming customer enquiries from a single address. Common examples include sales@, support@, accounts@, or info@. Because all messages live in one place, any team member can see what has been replied to and what still needs attention. The shared calendar is also useful for booking appointments or tracking job schedules.

Typical Use Cases

• Customer sales and support enquiries
• Accounts payable and invoicing
• General business enquiries via info@ or contact@
• Team calendar coordination for bookings or site visits

When to Use a Distribution List

Use a distribution list for internal broadcasts where you simply need to notify several people at once. Examples include all-staff@, managers@, or project-team@. Because each recipient gets a copy in their own inbox, it is less suitable for customer-facing addresses where you need to track replies and avoid duplicate responses.

Typical Use Cases

• Internal company announcements
• Department notifications
• Project team updates

Setting Up a Shared Mailbox in Microsoft 365

Follow these steps to create a shared mailbox and grant your team access. You will need administrator permissions in your Microsoft 365 tenant.

1. Sign in to the Microsoft 365 admin centre at https://admin.microsoft.com.
2. In the left navigation, select Teams & groups, then choose Active teams & groups.
3. Click Add and choose Shared mailbox.
4. Enter a name for the mailbox, such as Sales Enquiries, and an email address like [email protected].
5. Click Create.
6. Once created, select the shared mailbox from the list.
7. Under Members, click Edit members.
8. Add the staff members who need access and click Save.
9. Under Email forwarding, ensure forwarding is disabled if you want messages to remain in the shared mailbox rather than being sent to personal inboxes.

Shared mailboxes do not require a separate licence as long as they stay under 50 GB. Each user accessing the mailbox must have their own Microsoft 365 licence.

Granting Send As and Send on Behalf Permissions

By default, members can read items in a shared mailbox but cannot send emails from that address. To allow staff to reply as sales@, you need to assign send permissions.

1. In the Microsoft 365 admin centre, go to Teams & groups > Active teams & groups.
2. Select the shared mailbox.
3. Under Mailbox permissions, choose Send as or Send on behalf.
4. Click Edit, add the relevant users, and save your changes.
5. Ask users to restart Outlook or Outlook on the web for the new permissions to appear.

Send as makes the email appear to come directly from the shared mailbox address. Send on behalf shows "User on behalf of Shared Mailbox" in the From field. For customer-facing addresses, Send as is usually the better choice.

Opening the Shared Mailbox in Outlook

After permissions are granted, team members need to open the shared mailbox to access it.

Outlook on the Web

1. Sign in to Outlook on the web with your own Microsoft 365 account.
2. Click your profile picture or initials in the top-right corner.
3. Select Open another mailbox.
4. Enter the shared mailbox email address (for example, [email protected]) and click Open.

Outlook for Windows

1. Open Outlook and sign in with your own account.
2. The shared mailbox should appear automatically in your folder list after permissions are applied and Outlook is restarted.
3. If it does not appear, go to File > Account Settings > Account Settings, select your account, click Change, then More Settings > Advanced, and add the shared mailbox under Open these additional mailboxes.

Managing Centralised Email Signatures

When upgrading from generic login details or IMAP/POP3 accounts, it is important to apply consistent email signatures across shared mailboxes. Microsoft 365 does not include a built-in organisation-wide signature tool for shared mailboxes in the admin centre. Many Brisbane businesses use third-party signature management tools or train staff to apply a standard template manually.

Manual Signature Setup in Outlook on the Web

1. Open Outlook on the web and sign in with your own account.
2. Click the Settings gear icon.
3. Select Mail > Compose and reply.
4. Under Email signature, enter your signature text and formatting.
5. When replying from a shared mailbox, select the shared address in the From field before inserting your signature.
6. Click Save.

Preventing Emails from Landing in Client Junk Folders

Moving from cPanel webmail or shared logins to Exchange Online can improve deliverability, but only if your DNS records are configured correctly. If outgoing emails from sales@ or info@ are going to clients' spam folders, check the following.

DNS Records to Verify

• SPF: Include Microsoft 365 in your Sender Policy Framework record so receiving servers know your domain authorises Exchange Online to send mail.
• DKIM: Enable DomainKeys Identified Mail in the Microsoft 365 admin centre or Exchange admin centre to add a digital signature to outgoing messages.
• DMARC: Publish a DMARC policy to tell receiving servers how to handle messages that fail SPF or DKIM checks.

Checking the Exchange Admin Centre

1. Sign in to the Exchange admin centre at https://admin.exchange.microsoft.com.
2. Go to Mail flow > Message trace to review how mail is routed and check delivery reports.
3. Review Protection > Anti-spam policies to ensure legitimate outbound mail is not being flagged.

If you recently migrated from cPanel or IMAP/POP3, allow up to 48 hours for DNS changes to propagate globally. During this time, some emails may be delayed or marked as spam by external filters.

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