If your business uses Microsoft 365 — and in 2026, the vast majority of UK SMEs do — you have almost certainly encountered the question of whether to set up a shared mailbox or a distribution list. Both allow multiple people to receive email sent to a single address, but they work in fundamentally different ways and serve distinctly different purposes. Choosing the wrong one leads to missed emails, duplicated responses, confused customers, and frustrated staff.
This guide explains exactly what shared mailboxes and distribution lists are, how they differ, when to use each, and how to set them up correctly in Microsoft 365. We also cover Microsoft 365 Groups and dynamic distribution lists, giving you the full picture of collaborative email options available to your business.
What Is a Shared Mailbox?
A shared mailbox is a dedicated mailbox in Microsoft 365 that multiple users can access, read, and send email from. It has its own email address — such as info@yourcompany.co.uk or accounts@yourcompany.co.uk — and its own inbox, sent items folder, and calendar. Team members are granted access to the shared mailbox, which then appears alongside their personal mailbox in Outlook.
The critical characteristic of a shared mailbox is that it is a collaborative workspace. When someone sends an email to the shared mailbox address, it arrives in the shared inbox where any authorised team member can see it, read it, and respond to it. Replies are sent from the shared mailbox address, so the external sender sees a consistent business identity rather than an individual person's email. Other team members can see that a reply has been sent, reducing the risk of duplicate responses.
Shared mailboxes in Microsoft 365 do not require a separate licence, making them a cost-effective solution. However, if the mailbox needs more than 50GB of storage, you must assign a licence to it.
What Is a Distribution List?
A distribution list (also called a distribution group) is simply a way to send an email to multiple recipients using a single address. When someone sends an email to marketing@yourcompany.co.uk configured as a distribution list, Microsoft 365 delivers a copy of that email to each individual member's personal mailbox. There is no shared inbox — each person receives and manages the email independently in their own mailbox.
A distribution list is essentially a mailing list. It expands a single address into multiple individual deliveries. The recipients reply from their own email address, manage the email in their own inbox, and have no shared view of what others have received or responded to.
Key Differences at a Glance
| Feature | Shared Mailbox | Distribution List |
|---|---|---|
| Shared inbox | Yes — single inbox visible to all members | No — emails delivered to individual inboxes |
| Send as the group address | Yes — replies come from the shared address | No — replies come from the individual's address |
| Shared sent items | Yes — all members can see sent replies | No — sent items stay in each person's mailbox |
| Shared calendar | Yes — built-in shared calendar | No |
| Licence required | No (up to 50GB storage) | No |
| External senders | Can receive from external senders by default | May need configuration to accept external mail |
| Login required | No — accessed via delegation | No — delivered to personal inboxes |
When to Use a Shared Mailbox
Shared mailboxes are the right choice whenever you need a team to collaboratively manage incoming email and present a unified identity to external contacts. Here are the most common use cases.
Customer service and support. An address like support@yourcompany.co.uk as a shared mailbox ensures every customer enquiry is visible to the whole support team. Anyone can pick up and respond to a query, and the customer always sees replies from the support address rather than an individual's email. Other team members can see when a query has been answered, avoiding embarrassing duplicate responses.
Accounts and finance. An accounts@yourcompany.co.uk shared mailbox allows your finance team to collaboratively manage invoices, payment queries, and supplier correspondence. The shared sent items folder creates an audit trail of all outgoing communication.
General enquiries. An info@ or hello@ shared mailbox is ideal for managing general business enquiries that could be handled by multiple team members.
Project-specific communication. For significant projects involving multiple team members, a project-specific shared mailbox keeps all correspondence in one place and accessible to everyone involved.
To prevent emails from being overlooked or handled by multiple people simultaneously, establish clear ownership rules within your team. Some businesses use Outlook categories or flags to indicate when someone is actively working on an email. Others assign specific team members to check the mailbox at specific times. The key is having a process — without one, shared mailboxes can become chaotic.
When to Use a Distribution List
Distribution lists are the right choice when you want to broadcast information to a group of people and do not need collaborative inbox management. Common use cases include the following.
Company-wide announcements. An allstaff@yourcompany.co.uk distribution list delivers announcements, policy updates, and company news to every employee. There is no need for a shared inbox because the communication is one-way.
Department broadcasts. A marketing-team@yourcompany.co.uk distribution list allows anyone in the business to send information to the entire marketing department without needing to know every individual's email address.
External mailing lists. Distribution lists can include external email addresses, making them useful for sending regular updates to clients, partners, or suppliers.
Use a Shared Mailbox When
- Multiple people need to respond from the same address
- You need visibility of what has been handled and what hasn't
- External contacts should see a team address, not an individual
- You need a shared sent items trail for audit purposes
- The inbox needs to be managed as a team workflow
Use a Distribution List When
- You need to send information to a group of people
- Recipients will reply individually, not as a team
- There is no need for a shared view of incoming mail
- Communication is primarily one-directional
- You simply want a convenient group email address
What About Microsoft 365 Groups?
Microsoft 365 Groups are a newer collaboration option that blurs the line between shared mailboxes and distribution lists. A Microsoft 365 Group creates a shared mailbox, a shared calendar, a SharePoint document library, a OneNote notebook, and a Planner board — all connected under a single group identity.
Groups are powerful for teams that need more than just shared email. If your team needs to share files, manage tasks, and communicate via email from a single identity, a Microsoft 365 Group may be more appropriate than a standalone shared mailbox. However, Groups come with more complexity and can create sprawl if not managed carefully.
Common Mistakes and How to Avoid Them
Using a distribution list when you need a shared mailbox. This is the most common mistake. A distribution list for support@ means customer emails land in multiple individual inboxes with no shared visibility. Multiple people reply to the same email independently, and the customer receives conflicting responses. Use a shared mailbox for any address that requires collaborative response management.
Not configuring external sending permissions. By default, distribution lists in Microsoft 365 only accept email from internal senders. If customers need to email a distribution list address, you must explicitly enable external delivery in the Exchange admin centre.
Forgetting to manage membership. When staff leave the business, their access to shared mailboxes should be revoked and their membership of distribution lists removed. Failing to do this creates security risks — particularly if the former employee's personal mailbox is not immediately disabled, as they could continue receiving emails from distribution lists.
Exceeding shared mailbox storage limits. The free 50GB storage limit on shared mailboxes sounds generous, but a busy shared mailbox that receives attachments can fill up surprisingly quickly. Implement a retention policy to automatically archive or delete old emails, or assign a licence to increase the storage to 100GB.
Setting Up a Shared Mailbox in Microsoft 365
Creating a shared mailbox is straightforward for anyone with Microsoft 365 admin access. Navigate to the Microsoft 365 admin centre, select Teams and Groups, then Shared Mailboxes, and click Add a Shared Mailbox. Enter the display name and email address, add the members who should have access, and configure permissions for Send As and Send on Behalf. Members will see the shared mailbox appear in their Outlook client automatically, though it may take up to an hour to propagate.
For UK businesses handling personal data, remember that shared mailboxes are subject to UK GDPR. Ensure access is restricted to authorised personnel and that retention policies are configured appropriately. If the shared mailbox receives subject access requests or data-related enquiries, establish a clear process for handling these within the required timescales.
Choosing the Right Option for Your Business
The choice between a shared mailbox and a distribution list should be driven by the purpose of the email address. If the address needs collaborative management with a shared view of incoming and outgoing email, use a shared mailbox. If the address simply needs to deliver email to multiple people for informational purposes, use a distribution list. If you need broader collaboration including files and tasks, consider a Microsoft 365 Group.
Most businesses end up using a combination of all three. A typical UK SME might have shared mailboxes for info@, support@, and accounts@; distribution lists for allstaff@ and management@; and Microsoft 365 Groups for project teams and departments. The key is choosing the right tool for each specific purpose.
Need Help Setting Up Your Email Structure?
Cloudswitched helps UK businesses configure and optimise their Microsoft 365 environments, including shared mailboxes, distribution lists, and security policies. Get your email working the way your team needs it to.
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