Microsoft 365 Business Mailboxes Are Increasing to 100GB

The bigger mailbox has started showing up.

Microsoft is increasing the primary mailbox limit from 50GB to 100GB for users with Microsoft 365 Business Basic, Business Standard and Business Premium. Most people will never notice the change, but for a small number of users who have spent years pushing against the old 50GB limit, it’s a welcome improvement. It also means that some accounts may no longer need an extra Exchange Online Plan 2 license.

Why the second license was there

It wasn’t a mistake. It solved a real problem.

The regular Business plans came with a 50GB mailbox. Most people never come close. But a few do: the executive who’s kept every email since 2011, or the long-tenured employee whose inbox has years of emails they still need to reference. Once a mailbox fills, you either spend time pruning it or pay about $8 per month to double it to 100GB.

For our clients, that second license has almost always been there for one reason: to make the mailbox bigger. For someone whose time is better spent elsewhere, paying the extra $8 was usually cheaper than constantly managing the mailbox. It bought enough headroom that the problem largely disappeared.

Which Microsoft 365 Business Plans Get 100GB Mailboxes?

Microsoft 365 Business Basic, Business Standard and Business Premium are eligible for the increase to a 100GB primary mailbox. The change does not increase standalone Exchange Online Plan 1 mailboxes, which remain limited to 50GB.

The jump from 50GB to 100GB is now becoming part of the regular Microsoft 365 Business plans.

If mailbox size was the only reason an account had Exchange Online Plan 2, that extra license may no longer be necessary once the mailbox has been upgraded.

Check before you cancel

The rollout is gradual, so confirm the 100GB mailbox has actually reached each account before you remove its license. Not every mailbox flips on the same day. If you remove Plan 2 from an account that’s still limited to 50GB and already using more than that, the mailbox lands over its limit and can stop receiving mail until it’s cleared.

One more check: if an account was assigned Exchange Online Plan 2 for something beyond mailbox size, such as Litigation Hold or other compliance features, make sure those capabilities aren’t still needed before removing it.

The upshot

For most people, this update won’t change anything day to day. They’ll simply have more room before ever needing to think about mailbox limits.

For the small number of users carrying an extra Exchange Online Plan 2 license solely for mailbox size, it may also be an opportunity to simplify licensing and eliminate an unnecessary monthly cost.

If you’re one of our clients, we’re happy to help identify those accounts, verify they’ve received the 100GB mailbox, and remove the extra license at the right time.

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FAQs About Microsoft 365 Business Mailboxes

Which Microsoft 365 plans are getting 100GB mailboxes?

Microsoft 365 Business Basic, Business Standard and Business Premium are eligible for an increase from a 50GB primary mailbox to 100GB. The rollout is gradual, so not every user will receive the increased mailbox size at the same time.

Does Exchange Online Plan 1 also increase to 100GB?

No. Standalone Exchange Online Plan 1 mailboxes remain limited to 50GB. The 100GB mailbox increase applies to eligible Microsoft 365 Business plans.

Do I still need Exchange Online Plan 2 for a 100GB mailbox?

Possibly not. If Exchange Online Plan 2 was added only to increase a user’s mailbox from 50GB to 100GB, the extra license may no longer be necessary once that user’s Microsoft 365 Business mailbox has been upgraded. However, Plan 2 may still be needed for other features.

When can I remove an Exchange Online Plan 2 license?

You should confirm that the user’s mailbox has actually been increased to 100GB before removing Exchange Online Plan 2. Removing the license too early could leave a mailbox over its storage limit and prevent it from receiving new email.

How can I check whether a Microsoft 365 mailbox has been upgraded to 100GB?

A Microsoft 365 administrator can review the user’s mailbox settings and licensing to confirm the current storage limit. If you are unsure, your IT provider can verify the mailbox size and determine whether any additional Exchange licenses are still needed.