Business email and office suites · Comparison
Fastmail for Business vs Microsoft 365 Business
2 products compared side by side: what you pay for with each one first, then the five access facts, entry prices, recorded plan limits and the bottom line of each review. The evidence note under the table says how each product was checked.
Side by side
| Metric | Fastmail for Business | Microsoft 365 Business |
|---|---|---|
| What you're paying for | Worth the priceEmail, calendars and contacts on your own domain with 60 GB per user for $5 a month on 12-month terms, with open protocols and a documented API. | Worth the priceA 100 GB Exchange mailbox, 1 TB of OneDrive and Office for the web per user from $5.40 a month, with desktop Office apps one plan up. |
| Overall score | 5.7 | 7.6Best |
| Free option | 30-day free trial | 30-day free trial |
| Card to start | No card needed | Card required |
| Getting access | Self-serve | Self-serve |
| Starter priceCheapest paid plan | $3/user/mo | $5.40/user/mo |
| Pricing model | Per seat | Per seat |
| Pricing page | Public prices | Public prices |
| Billing unit | Per user per month; cheaper on 12-, 24- and 36-month terms | Per user per month; up to 300 users across all Business plans |
| Free option | No free plan; 30-day trial for 5 active users, no card | No free plan; one-month trial for up to 25 users, credit card required |
| Reference scenario (5 users, annual) | $25/mo on Standard ($5 × 5), computed | $27/mo on Business Basic (no Teams) ($5.40 × 5), computed; $35 with Teams |
| Month-to-month price | $6 per user on Standard ($4 / $10 for Basic / Professional) | $6.48 per user on Business Basic (no Teams); $8.40 with Teams |
| Storage per user | 6 GB (Basic), 60 GB (Standard), 150 GB (Professional), per user | 100 GB mailbox + 50 GB archive and 1 TB of OneDrive (1.5 TB archive on Premium) |
| Domains, aliases and catch-all | From Standard: 100 domains plus 1 per user, 600 aliases plus 15 per user, catch-all | Up to 5,000 domains, 300 to 400 aliases per user; no catch-all stated |
| Office apps | None; file storage with WebDAV | Office for the web and mobile on Basic; desktop apps from Standard |
| Video meetings | Not offered | Teams for 300 with recording in the plans with Teams |
| Retention and eDiscovery | Retention archive on Professional ($9); no eDiscovery | Litigation hold and eDiscovery export on Premium ($22); archiving add-on $3 |
| SOC 2 / ISO 27001 | No SOC 2 certification pursued; ISO 27001 not stated | Office 365 in SOC 2 Type II and ISO 27001 scope (Service Trust Portal) |
| HIPAA BAA | Not offered (not HIPAA compliant) | Included in the data protection addendum by default |
| EU data storage | EU or US primary storage on every plan; replica, backups and logs in the US | EU Data Boundary for EU and EFTA sign-ups |
| SAML SSO | Not offered | Single sign-on for apps with Entra ID on every plan |
| Mailbox export | ZIP per folder for each user (format not stated); no admin export of all users | PST from classic Outlook per user; admin eDiscovery export on Premium |
| Bottom line | From its public pages, Fastmail is a focused email, calendar and contacts service with 60 GB per user for $5, open protocols and no lock-in. It has no office suite, meetings, SSO or SOC 2 report, and its help articles disagree on a few limits and deletion periods. | From its public pages, Microsoft 365 gives a large mailbox and 1 TB of OneDrive per user at a low price, with shared mailboxes, an audit log and a BAA on Business Basic. Retention and eDiscovery sit on Premium or add-ons, and refunds and seat cuts are limited to 7 days. |
Evidence: Fastmail for Business: facts checked 2026-10-16 from its public sign-up and pricing pages, no completed hands-on run; Microsoft 365 Business: facts checked 2026-10-16 from its public sign-up and pricing pages, no completed hands-on run. Prices in USD as listed, excluding tax. "–" means not recorded.
When to pick each
In the words of each review, with the date its facts were checked.
From our Fastmail for Business review
Checked Oct 16, 2026- Pick Fastmail for Business when
- You want catch-all addresses, open protocols and cancellation at any time without penalty.
- Pick Microsoft 365 Business when
- You need office apps, Teams meetings, SSO or a HIPAA BAA.
Entry price
Baseline: each product's cheapest paid plan, per month. Included usage differs, so read the line under each price.
- Fastmail for BusinessBasic$3/user/mo12-month terms; $4 month to month; $2.80 on 36 months
- 6 GB per user (5 GB of mail, 1 GB of files)
- Own-domain addresses only with a Standard or Professional admin
- Web and mobile apps only: no IMAP, POP or API tokens
- Microsoft 365 BusinessBusiness Basic (no Teams)$5.40/user/moAnnual commitment; $6.48 month to month
- Exchange mail on your domain, 100 GB mailbox + 50 GB archive
- 1 TB of OneDrive per user
- Word, Excel, PowerPoint and Outlook for web and mobile
- No Teams meetings
Prices as listed on each pricing page, in USD per month, excluding tax. Observed: Fastmail for Business 2026-10-16, Microsoft 365 Business 2026-10-16.
Which one fits
- If you need to start today without a sales call
- Microsoft 365 BusinessSelf-serve sign-up, card required; the highest score of the 2 self-serve products here (7.6/10).
- If you want to try it without entering a card
- Fastmail for Business30-day free trial, no card needed; scored 5.7/10.
- Lowest starter price
- Fastmail for Business$3/user/mo for the Basic (12-month terms; no own domain) plan.
- Highest overall score
- Microsoft 365 Business7.6/10 (Good). The review shows the score breakdown and the run behind it.
Picked by fixed rules from the table above, not by hand. How we score
Full reviews
More in Business email and office suites
Add a product
Search by product name or by what it does, such as “email” or “feature flags”. 2 more fit in this comparison.