Distribution list, shared mailbox or Microsoft 365 group: which one to use

Distribution lists: one address, many inboxes

A distribution list is the simplest. Email sent to sales@ is copied into the personal inbox of everyone on the list. There is no shared storage, no shared calendar and no record of who replied. It suits announcements such as allstaff@, notifications from systems that only accept one address, and small teams where each person handles their own replies.

The weakness is coordination. If a customer emails sales@ and three people see it, each may assume someone else is answering, or all three answer. Replies go from each person's own address, so the customer ends up talking to an individual rather than the team. Use a distribution list when that is fine.

Distribution lists also do not keep a history in one place. If the person who handled a customer leaves, their replies leave with their mailbox unless someone takes it over. For anything where a customer may come back months later expecting the business to remember the conversation, that is a real drawback.

Shared mailboxes: one inbox, worked by a team

A shared mailbox is a real mailbox that several people open. Everyone sees the same messages, the same read and unread status, and replies can be sent from the shared address. When one person files an email, it is filed for everyone. This suits accounts@, support@ and bookings@, where the customer should deal with the business rather than a person, and where the team needs to see what has been handled. Shared mailboxes do not come with a shared file library or a team chat. They are focused on email. That is often a strength: a reception team wants one inbox and nothing more.

Microsoft 365 groups: email plus collaboration

A Microsoft 365 group bundles a shared inbox-style conversation space, a calendar, a SharePoint document library, a Planner board and a OneNote notebook. When you create a team in Teams, a group is created behind it. Groups suit a project team, a department or a client account where people need shared files and planning as well as email.

The group inbox works differently from a shared mailbox. Members can choose to receive group emails in their own inbox or only see them in the group, and replies go to the whole group by default. For external customer correspondence, that model can be confusing. Groups shine for internal teams, less so as a public-facing address.

Security groups and mail-enabled security groups

There is a fourth option most small businesses can ignore at first: security groups, used to grant access to files, apps and settings. A mail-enabled security group also works as a distribution list. They are useful when the same set of people should both receive email and have access to a folder, such as a finance group that receives finance@ email and has access to the finance library. If the office is growing and permissions are getting complicated, planning groups around roles rather than individuals pays off. A new accounts administrator then gets added to one group and inherits everything the role needs.

Choosing in practice

Ask three questions. Does the customer need to see replies from the business rather than a named person? If yes, use a shared mailbox. Do the people also need shared files, a calendar or a Teams space? If yes, a group or team. Is it just an announcement or notification that each person handles alone? A distribution list will do.

Some real examples: allstaff@ is a distribution list; info@ for a dental clinic is a shared mailbox; a fit-out project for a client, with drawings, a task board and an internal chat, is a team with its group; and alerts@ for monitoring notifications is a distribution list sent to the two people who care.

Converting between them

Getting it wrong is fixable but fiddly. A distribution list can be upgraded to a Microsoft 365 group with a built-in tool in many cases. Converting a group to a shared mailbox, or the reverse, generally means creating the new one and moving the address across, which takes some planning so no mail is lost during the switch. Note old messages from the previous type do not always come with you.

Before creating a new address, check the list of existing ones. Small offices often accumulate several overlapping addresses, such as office@, info@, enquiries@ and hello@, each a different type, with nobody sure which ones are monitored. A tidy-up that consolidates them into one or two well-managed addresses is a quick win.

When consolidating, keep the old addresses working as aliases on the new mailbox for at least a year, because customers, suppliers and online directories will keep using them. Update your website, invoices and listings in one sweep so the old addresses gradually fall out of use. Then retire them once incoming mail to them has dried up.