Shared Mailbox vs Distribution List vs Group: Picking info@

Each of these three objects looks similar from the Microsoft 365 admin center, but they behave very differently once real people start using them daily.

Shared Mailbox

A shared mailbox is a real mailbox with an inbox, sent items, and folders that multiple people log into using their own credentials. No separate license is required to create one, it holds up to 50 GB of mail by default, and Microsoft caps it at 25 concurrent users for practical performance reasons, according to the Microsoft shared mailbox documentation. That's the right tool when staff need to see and reply to the same threads, mark things read, and avoid duplicate responses to a customer. The catch: you cannot stop someone with delete permissions from deleting a message outright, there's no built-in way to add an outside partner or vendor as a true member, and once you build it as a shared mailbox you cannot later convert it into a Microsoft 365 Group. If there's any chance you'll want Teams channels or a shared Planner board tied to that address down the road, don't start here.

Distribution List (Distribution Group)

A distribution list is the oldest, simplest object of the three: it's a broadcast address. Mail sent to it fans out to every member's individual inbox, full stop. There's no shared inbox, no shared sent folder, no collaborative anything. It's genuinely useful for things like "all-staff announcements" or "everyone in accounting" where you just need one address that reaches a group of people, and each person manages the message in their own mailbox. It is the wrong choice for a customer-facing address like info@ or dispatch@, because nobody has visibility into what a coworker already answered.

Microsoft 365 Group

A Microsoft 365 Group is the modern, connected version of a team. It comes with a shared inbox and calendar, but also a Teams channel, a Planner board, a SharePoint document library, and the ability to add outside guests with controlled permissions, per the Microsoft group comparison guide. If dispatch needs to coordinate with an outside trucking partner, or your sales team wants a shared address that's also tied to a Teams channel for internal chatter, this is the object you want. The downside is governance: M365 Groups sprawl fast if nobody owns naming conventions and expiration policies, and each member typically needs an appropriate Microsoft 365 license.

Shared mailboxes are free up to that 50 GB ceiling, but two things push you into paid territory fast. First, if mail volume grows past the default size, you need an Exchange Online Plan 2 license (or Plan 1 plus Exchange Online Archiving) assigned to the mailbox to unlock auto-expanding archive storage. Second, if your compliance obligations require litigation hold on that mailbox, that also requires a Plan 2 license or Plan 1 with the archiving add-on. We've seen Texas firms discover this mid-legal-hold, which is the worst possible time to find out your "free" mailbox needs a paid license attached before it can legally retain everything it's supposed to. If your industry has records retention requirements, loop this into your HIPAA or FTC Safeguards Rule planning before you build the mailbox, not after.

The 25-user concurrent access ceiling on shared mailboxes isn't arbitrary; it's a performance and support boundary from Microsoft. If your dispatch team has more than two dozen people actively logging into the same mailbox throughout the day, you're already outside supported territory and should be looking at a Group with Teams integration instead. And because a shared mailbox has no concept of guest access, any scenario involving an outside vendor, contractor, or partner company needs a Group from day one. Trying to retrofit that later means recreating the address and losing continuity, which is exactly what tripped up the logistics company we mentioned earlier.

For most small and mid-size Texas offices, info@ works well as a shared mailbox because it's simple, free, and gives full visibility into every message. Dispatch@ depends on whether outside carriers or contractors need access; if they do, build it as a Microsoft 365 Group with a dedicated Teams channel so dispatch conversations and customer email live in the same place. Either way, get someone who manages Exchange administration and Entra ID permissions properly to set delete restrictions, retention policies, and ownership before go-live, not after a departing employee cleans out three years of customer history.

This is a small decision with outsized consequences once customer data and legal retention get involved. If you're not sure which object your current info@ or dispatch@ address actually is, or whether your licensing already covers archiving and litigation hold, that's worth a quick audit as part of a broader Microsoft 365 managed services review, alongside your cloud services and network setup.

Can I convert a shared mailbox into a Microsoft 365 Group later?

No. Once an address is built as a shared mailbox, Microsoft does not offer a supported path to convert it into a Group. You'd need to recreate the address as a Group and manually migrate mail history, which breaks continuity for an active customer-facing inbox.

Do I need a license for a shared mailbox?

Not for basic use up to 50 GB. You only need a license, specifically Exchange Online Plan 2 or Plan 1 with Exchange Online Archiving, when the mailbox needs auto-expanding archive storage or litigation hold.

Can outside vendors or partners be added to a shared mailbox?

No, shared mailboxes don't support true outside guest access. If dispatch or another function needs to loop in an external partner with controlled permissions, a Microsoft 365 Group is the right object.

What happens if someone deletes an email from a shared mailbox by mistake?

There's no built-in way to block delete permissions for individual users within a shared mailbox. Recovery depends on your retention policy and whether litigation hold or archiving is enabled, which is another reason to plan licensing before go-live.

If your Houston or Round Rock office is still running on guesswork for info@, dispatch@, or any shared address, request a free IT assessment or contact us and we'll map out the right object, licensing, and retention policy before it becomes a problem.