Shared Mailbox vs Distribution List vs Microsoft 365 Group

Pick wrong and you get missed emails, duplicate replies, or a license bill you didn't need. Below are a side-by-side comparison, a decision table, and the questions small business owners ask us most.

Shared mailbox vs distribution list vs Microsoft 365 group: how do they compare?

	Shared mailbox	Distribution list	Microsoft 365 group
What it is	One inbox that several people open and answer from	An address that copies each message to every member's own inbox	A membership that comes with a group inbox, calendar, SharePoint document library, Planner and OneNote
Who sees replies	Everyone with access to the mailbox	Only whoever is copied on each reply	Every member, in the group's shared inbox
Calendar and files	A shared calendar, no file library	No	Shared calendar and SharePoint files
Microsoft Teams	Not used by Teams	Can be added to a team, but only its current members are added	Every team is built on a Microsoft 365 group
Outside people	Only people inside your organization can open it	Can receive outside email if an admin allows it	Guests can be members, and outside senders can be allowed
Limits	50 GB without a license; up to 25 users	Up to 100,000 members	Group mailbox of 50 GB; more than 1,000 members, but only 1,000 can open conversations at once
Cost (November 2026)	Free up to 50 GB; 100 GB needs Exchange Online Plan 2	Included	Included in Business Basic, Standard and Premium

Sources, checked on November 7, 2026: Microsoft's guides to shared mailboxes, comparing group types, Microsoft 365 Groups for administrators and Exchange Online limits.

Which one should you use?

Your situation	Use	Why
info@, billing@ or support@, answered by 2 to 25 people	Shared mailbox	One inbox, so everyone sees what was handled, and no license under 50 GB
Announcements to all staff, all managers or one office	Distribution list, or a dynamic distribution group that fills itself by department or location	Broadcast only; nobody needs a shared record of replies
A department or project team that shares files, a calendar and a Teams channel	Microsoft 365 group	One membership grants the inbox, calendar, SharePoint files, Planner and Teams
More than 25 people answering the same address	Microsoft 365 group, or a help desk tool	Microsoft caps a shared mailbox at 25 users
Working with an outside partner or contractor	Microsoft 365 group with guest access	Outside people cannot open a shared mailbox
Granting access to a SharePoint site and emailing the same people	Mail-enabled security group	It carries permissions and an email address in one object
A former employee's email	Convert their mailbox to a shared mailbox	Keeps the mail reachable and frees the license under 50 GB

Frequently asked questions

What's the difference between a shared mailbox, a distribution list, and a Microsoft 365 group?

A shared mailbox is one inbox several people open and answer from, like info@ or billing@. A distribution list is just an address that copies a message to every member's own inbox. A Microsoft 365 group adds a shared inbox, calendar, SharePoint files, and Planner, and can connect to Teams.

Is a Microsoft 365 group the same as a distribution group?

No. A distribution group, the admin center's name for a distribution list, only passes mail along to its members. A Microsoft 365 group has its own mailbox, calendar and SharePoint library, so members can read past conversations they were never copied on, and it is the membership behind every team in Teams. The two don't nest either: Microsoft 365 groups can't be members of distribution groups.

Which one should we use for info@ or support@?

A shared mailbox. Everyone sees the same inbox, so when one person answers or files a message, the rest can see it was handled. Send that address to a distribution list instead and every member gets a separate copy, with no way to know who replied. That's how customers get two answers, or none.

Does a shared mailbox need its own license?

Usually not. Microsoft says a shared mailbox doesn't need a license up to 50 GB, though everyone who opens it needs a licensed mailbox. Going to 100 GB takes an Exchange Online Plan 2 license, listed at $8.00 per user per month on annual billing as of October 2026 on Microsoft's Exchange Online plans page. An archive or a litigation hold takes Plan 2, or Plan 1 plus Exchange Online Archiving. Our guide to Microsoft 365 storage limits covers the other quotas.

Can people sign in to a shared mailbox with its own password?

They shouldn't. Microsoft's guidance is direct: "Always block sign-in for the shared mailbox account and keep it blocked." Staff open the mailbox through their own account, so every action ties back to a real person with MFA. A shared password nobody owns is exactly what attackers look for.

How many people can use one shared mailbox?

Microsoft says a shared mailbox supports a maximum of 25 users. Past that, people see connection failures or duplicated messages. If more than 25 people need the same inbox, Microsoft points you to a Microsoft 365 group. That usually also means it's time to look at a real ticketing tool.

When does a distribution list make more sense?

When the job is broadcasting, not answering. Microsoft describes distribution groups as best for situations where you need to broadcast information to a set group of people, like "everyone at the company" or "all project managers." Nobody needs to see who replied. Distribution lists cost nothing, and admins can allow or block outside senders. If the list should follow your org chart, a dynamic distribution group picks its members by department or location each time a message is sent.

When should we use a Microsoft 365 group instead?

When the team shares more than email. A Microsoft 365 group gives members a group inbox, a shared calendar, a SharePoint document library, and Planner, and it can be connected to Teams. It fits a project team or department, including one with outside guests. It doesn't fit a customer-facing inbox, where a shared mailbox is cleaner. Group files live in SharePoint, which our SharePoint vs OneDrive FAQ explains.

What should we do with a former employee's mailbox?

Convert it to a shared mailbox, give their manager access, then remove the license. Microsoft notes you can stop paying for it if it's under 50 GB. Don't delete the user account, because it anchors the mailbox. Block their sign-in first. Our IT offboarding FAQ covers the rest.

Can we send email as the shared mailbox?

Yes. Grant "Send As" so replies appear to come straight from info@, or "Send on Behalf" so they read "Jane on behalf of Info." Most businesses want Send As for customer-facing addresses. One limit to know: Microsoft says email sent from a shared mailbox can't be encrypted, because the mailbox has no sign-in of its own. Shared mailboxes also count against sending limits, which our Microsoft 365 outbound email limits guide explains.

Which option fits a small team?

Most teams of 5 to 50 people need all three, each in its place: a shared mailbox for every customer-facing address, one distribution list for all-staff announcements, and a Microsoft 365 group, usually created through Teams, for each department or project that shares files. Keep the number of groups small. Any user can create a Microsoft 365 group unless you limit it, so decide who may create them before Teams sprawl sets in.

What affects the cost, implementation and support of shared mailboxes and groups?

Cost is mostly licensing at the edges: a shared mailbox over 50 GB or one that needs an archive or hold, and Microsoft Entra ID P1 for groups whose membership updates automatically from user attributes, which Business Premium includes. Implementation means choosing names and addresses, setting Full Access and Send As permissions, and deciding who can create groups. Support is the ongoing part: changing membership when people join or leave, watching mailbox sizes, and reviewing or expiring groups nobody uses.

Not sure your mailboxes and groups are set up right, or paying for licenses you don't need? Our Microsoft 365 management service runs users, licensing, shared mailboxes, groups and Teams for your tenant month to month. Book a call, or see the rest of our IT services.