Microsoft 365 Email: Which Plans Include It, the Limits, and How to Set It Up

By The Uptime Report Team · Last reviewed: October 2026

Microsoft 365 email is a hosted Exchange Online mailbox you open at outlook.office365.com or Microsoft365.com: plans start at $4.00 per user per month for 50 GB, and Business Basic at $7.00 gives 100 GB.

What is Microsoft 365 email?

Microsoft 365 email is a mailbox hosted on Exchange Online, Microsoft’s cloud mail server, that you read in Outlook on the desktop, the web or a phone. Microsoft sells it inside Microsoft 365 suites and as two standalone plans; Exchange Online Plan 1 is the cheapest at $4.00 per user per month on an annual commitment (Microsoft, October 2026).

Exchange and Outlook are two different layers. Microsoft’s Exchange product page describes Exchange as “the server on the backend that stores and syncs your data” and Outlook as “the client on the frontend”. Buying Outlook alone does not buy a mailbox; the Exchange Online license does.

Microsoft’s support article on signing in to Outlook on the web sends work and school accounts to Microsoft365.com or directly to outlook.office365.com, and says Outlook.com “uses a personal Microsoft account”. That free consumer service gives 15 GB of email storage, and consumer Microsoft 365 subscribers are capped at 100 GB, so a staff member signed in to Outlook.com is in the wrong account.

Which Microsoft 365 plans include email, and what do they cost?

The eight plans most buyers compare all include an Exchange Online mailbox, from Exchange Online Plan 1 at $4.00 to Microsoft 365 E5 at $60.00 per user per month, annual commitment, as of October 2026. Business Basic, Standard and Premium carry 100 GB mailboxes; Plan 1 carries 50 GB, and the frontline F3 plan carries 2 GB. List prices for the suites changed on July 1, 2026, per Microsoft’s December 2025 pricing announcement.

Mailbox and archive sizes come from the storage tables on Microsoft Learn’s Exchange Online limits page (updated October 19, 2026). The Business plans are sold for 1 to 300 users, and the 300-seat cap is shared across the Business family of plans in one tenant: Microsoft’s plans FAQ says a tenant with 250 Business Premium seats can add only 50 more across all Business plans.

Two plans that look like email plans are not. Microsoft 365 Apps for business ($10.00) lists desktop Outlook and 1 TB of OneDrive storage in its plan highlights but no custom business email, and Microsoft 365 F1 ($3.00) carries “Exchange Kiosk for Teams calendar only”, not a mailbox, per Microsoft’s frontline comparison table. Business Standard at $14.00 is the cheapest plan with both a mailbox and desktop Office apps, the dividing line our Microsoft 365 business plans comparison prices seat by seat.

How do billing terms change what you pay and what you can cancel?

Microsoft 365 email costs 20% more on a monthly commitment than on an annual one: Business Basic is $7.00 per user per month annual and $8.40 monthly, so 10 users pay $168 more a year. The annual price buys less flexibility, because Microsoft refunds an annual term only within 7 days, and seats bought through a partner can be reduced only in that same window.

For an MSP, the CSP row is the contract clause that matters: a seat added for a temporary hire on an annual term is billable to the end of that term once 7 days pass. Write the commitment type per seat into the statement of work, and keep monthly-commitment seats for roles with turnover. Our guide to cancelling Microsoft 365 Business covers what happens to mailbox data after a cancellation.

How big is a Microsoft 365 mailbox?

A Microsoft 365 Business Basic, Standard or Premium mailbox holds up to 100 GB, double the 50 GB those plans carried before Microsoft’s 2026 packaging change. The Exchange Team says the increase rolled out from June to September 2026. Standalone Exchange Online Plan 1 stays at 50 GB, Plan 2 and the E3 and E5 suites hold 100 GB, and frontline F3 mailboxes hold 2 GB.

The Exchange Team post of August 19, 2026 explains three mechanics an admin will see in the tenant:

• The Business suite’s BPOS_S_STANDARD service plan grants 50 GB, and a new EXCHANGE_STORAGE_50GB service plan adds the other 50 GB, so both must be enabled.
• Quotas from two licenses are not added together; Exchange applies the highest single entitlement, so a Business suite plus Exchange Online Plan 2 still means 100 GB.
• A custom quota an admin set earlier, such as 20 GB, stays in place after the add-on arrives.

The archive is a separate allowance. Per Microsoft Learn’s limits tables, Business Basic and Standard include a 50 GB archive mailbox, while Business Premium, Exchange Online Plan 2 and the E3 and E5 suites start at 100 GB and auto-expand to 1.5 TB. Shared mailboxes need no license up to 50 GB; reaching 100 GB requires assigning an Exchange Online Plan 2 license to that shared mailbox.

Deleted mail is recoverable for 14 days by default, 30 at most. Microsoft 365 Backup, Microsoft’s paid add-on compared with third-party tools in our Microsoft 365 backup guide, lists at $0.15 per GB per month of protected mailbox and archive content, keeps Exchange restore points every 10 minutes for 52 weeks, and charges nothing for restores, per Microsoft Learn. Ten 20 GB mailboxes come to 200 GB, or $30 a month.

How do you move existing email into Microsoft 365?

The migration method depends on where the mail sits now. Microsoft Learn’s mailbox migration overview allows a cutover migration for up to 2,000 Exchange mailboxes but suggests 150 or fewer, uses IMAP migration for other hosts with a 500,000-item and 35 MB per-message ceiling, and moves mailboxes between two Microsoft 365 tenants only with a one-time per-user license.

IMAP is the usual path off a shared web host, and its gaps decide the quote: contacts and calendars move by hand, messages over 35 MB stay behind, and Microsoft says new mail sent to the old host after the migration isn’t migrated, so schedule the MX change for the same window as the final sync.

What are the Microsoft 365 email sending limits?

Each Microsoft 365 mailbox can send to 10,000 recipients in a rolling 24-hour window, with up to 1,000 recipients on one message and 30 messages per minute, per Microsoft Learn’s Exchange Online limits as of October 2026. A second, tenant-wide cap counts external recipients across all mailboxes, and mail sent from the default onmicrosoft.com domain is held to 100 external recipients a day.

Microsoft’s own example: a user who sends to 5,000 recipients at 09:00, 2,500 at 10:00 and 2,500 at 11:00 hits the 10,000 limit and cannot send again until 09:00 the next day. Microsoft Learn states that customers sending “legitimate bulk commercial email (for example, customer newsletters) should use third-party providers”.

How is the tenant-wide external recipient limit calculated?

The Tenant External Recipient Rate Limit (TERRL) equals 500 times the number of non-trial email licenses raised to the power 0.7, plus 9,500, per the Exchange Team’s TERRL announcement. A 10-license tenant can therefore reach about 12,006 external recipients a day across all mailboxes combined. Tenants younger than 31 days get 10% of that quota, and 25% from day 31 to day 60.

The 1, 10, 25, 100 and 1,000 rows match Microsoft’s published sample table; the 50 and 300 rows and every percentage column are our arithmetic from the same formula. The new-tenant columns matter for an MSP onboarding a client: a fresh 25-seat tenant can send to only about 1,426 external recipients a day in its first month, so a client mailing more than that stays on the old system until day 61.

How do you set up Microsoft 365 email on your own domain?

Setting up Microsoft 365 email on your own domain takes one verification TXT record plus four kinds of mail records: MX, an autodiscover CNAME, an SPF TXT record and two DKIM CNAMEs, then a DMARC TXT record. Microsoft Learn’s DNS setup guide gives TTL 3600 for each mail record and MX priority 0, and says to create mailboxes before the MX change so no mail is lost.

1. Add and verify the domain. In the Microsoft 365 admin center, add the domain and publish the TXT record it shows. Verification takes up to 10 minutes, and some registrars need up to 48 hours, per Microsoft Learn’s add a domain guide.
2. Create every user and shared mailbox first. Once the MX record changes, all new mail for the domain goes to Microsoft 365; old mail stays with the previous host unless you migrate it.
3. Publish the MX record. Host @, value copied from the admin center, priority 0, TTL 3600. Remove the old provider’s MX records or give them a higher number (lower priority). Exchange Online supports TTLs below 21,600 seconds (6 hours).
4. Publish the autodiscover CNAME. Host autodiscover, value from the admin center, TTL 3600. Outlook uses it to configure the account automatically.
5. Publish or edit the SPF TXT record. Microsoft’s SPF guide gives the value v=spf1 include:spf.protection.outlook.com -all. If an SPF record exists, merge the include into it: a domain may have only one SPF record, and RFC 7208 section 4.6.4 fails SPF after 10 DNS-querying terms.
6. Publish both DKIM CNAMEs, then turn DKIM signing on. Hosts selector1._domainkey and selector2._domainkey; copy both targets from the Defender portal or Get-DkimSigningConfig, then enable signing for the domain.
7. Publish DMARC at p=none. Host _dmarc, value such as v=DMARC1; p=none; pct=100; rua=mailto: plus a reporting mailbox you read.
8. Move to p=quarantine, then p=reject. Microsoft’s DMARC guide sets p=reject as the goal once reports show every legitimate sender passing.

DKIM targets come in two formats. Microsoft’s DKIM guide says custom domains added since May 2025 point at a dkim.mail.microsoft zone with a partition letter such as r or n, while older domains keep the selector1-contoso-com._domainkey.contoso.onmicrosoft.com format, and “the old and new formats can’t coexist for the same selector”. Copy targets from the portal instead of typing them.

Do Microsoft 365 email domains enforce DMARC?

Domains whose mail runs through Microsoft enforce DMARC more often than other domains, but many still stop at p=none. In our October 2026 DNS scan, 70.8% of top-10,000 mail domains with an MX record at Microsoft enforced DMARC with quarantine or reject, against 58.9% of other mail domains. In the long-tail sample the figures fall to 43.5% and 28.1%.

The figures are a new cut of the 15,000-domain dataset behind our DMARC adoption statistics report, which ranks domains by the Tranco list. Microsoft-hosted mail made up 15.9% of top-10,000 mail domains and 15.8% of the long tail. In the long tail, 55.7% of Microsoft-hosted domains sit at p=none or publish no record, which leaves step 8 of the setup list undone. An MX at Microsoft can also mean Exchange Online Protection filtering an on-premises server.

For an MSP, the long-tail figure is the sales case: more than half of the smaller Microsoft-hosted domains in the sample publish no DMARC policy that tells receivers to quarantine or reject forged mail. DMARC stops exact-domain spoofing only, so lookalike-domain phishing still needs the filtering layer described in our email security guide.

What changed for Microsoft 365 email in 2026?

Four changes in 2026 make older Microsoft 365 email guides wrong: suite list prices rose on July 1, 2026; Business plan mailboxes doubled to 100 GB between June and September 2026; Microsoft made SMTP AUTH Basic authentication off by default from the end of December 2026 (admins can still re-enable it); and the tenant-wide external sending formula changed for some tenants from September 14, 2026.

How should scanners and apps send mail through Microsoft 365?

Scanners and apps that send with a stored password should move now: Basic authentication goes off by default at the end of December 2026, and admins can re-enable it only until a removal date due in 2027. Microsoft Learn’s device and application guide lists four routes: SMTP client submission with OAuth on port 587, SMTP relay through a connector on port 25, Direct Send on port 25, and High Volume Email for internal mail.

Direct Send accepts unauthenticated mail that claims your own domain, and Microsoft Learn says most customers don’t need it. The Exchange Team’s Reject Direct Send post adds an opt-in block, Set-OrganizationConfig -RejectDirectSend $true, that is off by default and takes up to 30 minutes to apply; legitimate printers then need a partner connector. Basic-auth SMTP also isn’t compatible with Microsoft Entra ID security defaults, the baseline our Microsoft 365 security guide weighs against Conditional Access.

Which Microsoft 365 email plan fits your situation?

Pick the cheapest plan that clears your largest mailbox, your app needs and your seat count. Exchange Online Plan 1 at $4.00 covers email-only users under 50 GB; Business Basic at $7.00 adds 100 GB and Teams; Business Standard at $14.00 adds desktop apps; Business Premium at $22.00 adds the 1.5 TB archive; past 300 users the E3 and E5 suites apply.

What should an MSP check in a tenant before quoting?

Before quoting Microsoft 365 email work, check five settings that each map to a line in the statement of work: Basic-auth SMTP senders, the Reject Direct Send flag, DKIM status, the DMARC policy and the external sending quota. Each check uses a report, command or DNS lookup Microsoft documents, so no test sends are needed, and each finding becomes a fixed-price task with a deadline.

How we compiled this

We compiled this page in October 2026 from 34 primary documents: Microsoft’s US plan and pricing pages, Microsoft Learn service descriptions, setup, migration, mail-flow and backup guides, Partner Center policy, Exchange Team blog posts, Microsoft support articles and RFC 7208. Prices are US list prices on an annual commitment unless marked monthly. The DMARC table is a new cut of our own 15,000-domain DNS scan of October 19, 2026, grouped by whether each domain’s MX record points at a Microsoft host (mail.protection.outlook.com or mx.microsoft). We did not test mail delivery or set up a tenant.

Frequently asked questions

Is there a free trial of Microsoft 365 email?

Microsoft’s Business plans offer a one-month free trial that needs a credit card and converts to a paid subscription unless cancelled; Microsoft notes trial storage is limited. Exchange Online Plan 1 and Plan 2 show only a buy option on Microsoft’s Exchange plan page. Trial tenants also face a lower external sending cap than paid tenants.

Does a shared mailbox in Microsoft 365 need a license?

No, up to 50 GB. Users who open it need their own Exchange Online license, but the shared mailbox itself is free until it needs 100 GB, which requires an Exchange Online Plan 2 license, or litigation hold or an auto-expanding archive, which require Plan 2 or Plan 1 plus Exchange Online Archiving, per Microsoft Learn. Block sign-in for its system account.

What do Microsoft 365 email errors 550 5.7.236, 5.7.233 and 5.7.68 mean?

550 5.7.236 means the tenant hit the 100-external-recipient daily cap for onmicrosoft.com addresses (Microsoft Learn). 550 5.7.233 means the tenant exceeded its daily external recipient limit (Exchange Team). 550 5.7.68 means Reject Direct Send blocked an unauthenticated message using your own domain (Exchange Team); that sender needs a partner connector.

How many email aliases can a Microsoft 365 mailbox have?

About 300. Microsoft Learn’s Exchange Online limits list a recipient proxy address limit of 300 for Business and Enterprise suites and 400 for standalone plans, and note the true ceiling depends on address length, so 300 is the safe planning figure. The same table caps one message at 1,000 recipients.

Can you recover a deleted Microsoft 365 mailbox?

Yes, for 30 days. A user mailbox deleted in the Microsoft 365 admin center or with Remove-Mailbox stays soft-deleted and recoverable within 30 days while the account sits in the Microsoft Entra ID recycle bin, per Microsoft Learn. After that it is gone unless a backup or retention policy kept the content.

How long does Microsoft 365 keep Junk Email?

30 days. Microsoft Learn’s retention limits remove items from the Junk Email folder after 30 days on every Microsoft 365 plan, while the Deleted Items folder has no automatic limit. Items removed from Deleted Items stay recoverable for 14 days by default, and admins can raise that to 30 days per mailbox.

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