Business Basic, Standard, Premium or E3 and E5 for Your Migration

Licensing decisions made in a hurry before a migration tend to stick for years. The plan you pick sets the mailbox quota, whether users get desktop Office, whether you can manage their devices, and how much security tooling you have when something goes wrong.

This post compares the Business and Enterprise families in plain terms and covers the licensing details that specifically affect a migration.

The Business family

Business Basic, Standard and Premium are for organizations with up to 300 users. Basic gives Exchange Online with a 50 GB mailbox, Teams, SharePoint, 1 TB of OneDrive and the web and mobile versions of Office. Standard adds the installable desktop Office apps on up to five devices per user, plus webinar and booking features. Premium adds the security and management layer: Intune for device management, Defender for Business for endpoints, Entra ID P1 for conditional access, and Purview information protection.

For a company moving off on-prem Exchange, Premium is usually the right default. Conditional access to enforce MFA properly, Intune to push Outlook settings and manage phones, and endpoint protection in the same subscription solve most of the post-migration security list in one purchase. Standard fits when there is already a separate endpoint product and device management in place. Basic suits frontline or shared-desk staff who only need mail and Teams in a browser.

• Basic: mail 50 GB, Teams, OneDrive, web and mobile Office only.
• Standard: Basic plus desktop Office apps.
• Premium: Standard plus Intune, Defender for Business, Entra ID P1, Purview information protection.
• All three: 300 user cap per plan, mix and match allowed within it.

The Enterprise family

E3 and E5 have no user cap. E3 includes Exchange Online Plan 2 with a 100 GB mailbox and an auto-expanding archive, desktop Office, Windows Enterprise upgrade rights, Intune, and Entra ID P1. E5 adds the advanced security and compliance stack: Defender for Office 365 Plan 2, Defender for Endpoint Plan 2, Entra ID P2, Purview advanced eDiscovery and audit, Teams Phone, and Power BI Pro.

One thing that changed: in many markets Microsoft now sells Enterprise plans without Teams, with Teams Enterprise as a separate add-on. Check the exact SKU names you are quoted and confirm Teams is included before you count on it. Business plans still include Teams.

The practical trigger for E3 in a migration is mailbox size. If a meaningful number of users have mailboxes over 50 GB, E3 for those users is cleaner than fighting to shrink them, and the archive covers whatever remains. The trigger for E5 is usually a compliance requirement or a security team that wants the full Defender and Purview stack, not the migration itself.

Standalone and add-on plans

Not every account needs a suite. Exchange Online Plan 1 and Plan 2 exist as standalone mail licenses, and Exchange Online Kiosk is a small mailbox for users who only need web access. Exchange Online Archiving is an add-on that gives an auto-expanding archive to Plan 1 mailboxes. Frontline plans, F1 and F3, cover deskless workers at a lower price with smaller mailboxes and web-only apps.

Shared mailboxes, resource mailboxes and distribution groups need no license unless the shared mailbox exceeds 50 GB, gets an archive or goes on litigation hold. Service accounts that send mail through SMTP AUTH do need a mailbox license.

Licensing details that affect the migration itself

Assign licenses before you move a mailbox. A hybrid move into an unlicensed cloud account works, but the mailbox enters a grace period and gets disabled if a license is not assigned within it. In cutover and IMAP migrations the mailbox must exist first, which means the license must be assigned first.

The quota is checked at the end of the move, not the start. A 60 GB mailbox moved to a Business Standard user copies for hours and then fails. Match large mailboxes to E3 or shrink them before the batch.

Group-based licensing through Entra ID keeps this manageable. Put users in a group per license profile, assign the licenses to the group, and the migration CSV becomes the group membership list.

Connect-MgGraph -Scopes "User.ReadWrite.All", "Organization.Read.All"
Get-MgSubscribedSku | Select SkuPartNumber, ConsumedUnits, @{n="Total";e={$_.PrepaidUnits.Enabled}}
Get-MgUser -Filter "assignedLicenses/`$count eq 0 and userType eq 'Member'" -ConsistencyLevel eventual -CountVariable c -All | Select DisplayName, UserPrincipalName

A simple way to decide

Start with the headcount and the biggest mailbox, then ask what security and device management you already have.

1. Over 300 users, or expecting to be: Enterprise plans, E3 as the base.
2. Under 300, no separate endpoint and MDM products: Business Premium as the base.
3. Under 300, endpoint and MDM already covered: Business Standard, with Premium for admins and finance.
4. Users with mailboxes over 50 GB: E3 for those users, or Exchange Online Archiving added to their Business plan and an archive policy.
5. Frontline, kiosks, shared desks: Business Basic or F3.
6. Compliance requirements with eDiscovery and retention across Teams and SharePoint: E5 or the Purview add-ons, decided with whoever owns compliance.

Frequently asked questions

Takeaway

Pick the plan from headcount, mailbox sizes, and what security and device management you already own. Business Premium covers most small companies, E3 covers big mailboxes and larger organizations, and E5 is a compliance and security decision rather than a migration one. Assign the licenses through groups before the first batch moves, and the quota surprises go away.