Shared Mailbox vs Distribution List: 9 Questions Owners Ask

Use a shared mailbox when a team needs to work the same inbox, a distribution list when you just need to email a group, and a Microsoft 365 group when the team also needs a shared calendar, files, or Teams. Pick wrong and you get missed emails, duplicate replies, or a license bill you didn't need. These are the questions small business owners ask us most.

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.

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. You'll need Exchange Online Plan 2, or Plan 1 plus Exchange Online Archiving, to go to 100 GB, turn on an archive, or put it on litigation hold.

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.

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. It doesn't fit a customer-facing inbox, where a shared mailbox is cleaner.

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. Shared mailboxes also count against sending limits, which our Microsoft 365 outbound email limits guide explains.

Not sure your mailboxes and groups are set up right, or paying for licenses you don't need? Book a complimentary Microsoft 365 review and we'll sort it out. See our Microsoft 365 management service and the rest of our IT services.