Fastmail Cost Per User for Business: Plans and Limits

Fastmail cost per user for business is a per-seat number, and the honest way to read it is as email hosting pricing rather than a productivity-suite subscription. Fastmail sells mailboxes, calendars, contacts and a modest file allowance. It does not sell documents, spreadsheets or video conferencing, so weighing its seat price against a full suite is weighing two different purchases.

That distinction moves the maths more than any individual tier does. This guide covers what each business tier includes as of August 2026, the two places teams routinely over-buy or under-buy, and a worked example of sizing seats.

The short answer#

Fastmail bills business email per user, per month. As of August 2026 there are three business tiers, and you can put different people on different tiers rather than buying one plan for everyone.

The tiers differ by feature access as well as capacity. Basic is the cheapest seat and the most restricted. Standard is the tier most businesses actually want. Professional adds storage and a tamper-proof retention archive.

There is no permanent free tier. Fastmail offers a trial of up to 30 days, then it is paid, with discounted 12-, 24- and 36-month terms alongside monthly billing.

• Basic: smallest storage allowance, Fastmail's own web and mobile apps only, no custom domain of its own, no third-party app access.
• Standard: custom domains, Masked Email, third-party app access, and the storage allowance most people need.
• Professional: the largest storage allowance plus a retention archive that admins enable per user.
• Shared addresses like support@ or sales@ are included on every tier and consume no paid seat.

The criteria that actually decide your per-user cost#

Most Fastmail cost comparisons stop at the tier table. That is the wrong place to stop, because two teams of identical headcount can land on very different bills.

The second criterion below is where teams lose money in both directions. Buying every seat at Standard when half the staff only open webmail overpays. Buying Basic seats for people who use Apple Mail underpays, and you find out the week after you migrate.

• Seats, not addresses. You pay for people who need their own login and mailbox. Shared and forwarding addresses do not add a seat.
• Tier mix. Because tiers mix inside one account, the real cost driver is how many people need third-party app access and Masked Email, not headcount.
• Storage per user, not pooled. One person with a decade of attachments does not drag the whole account up a tier.
• Commitment length. Monthly, 12-, 24- and 36-month terms are offered, and the discount deepens as the term lengthens.

What each Fastmail business tier includes#

Drawn from Fastmail's own published plan comparison, checked August 2026. Storage is per user rather than pooled, and mail and file allowances are counted separately.

The Basic seat is a different product, not a smaller one#

The most consequential line in that table is third-party app access, and it is the one that does not look like a cost decision.

Standard and Professional include it. Basic does not. A Basic seat can use Fastmail's web interface and Fastmail's own mobile apps, and nothing else. No Apple Mail, no Outlook desktop, no Thunderbird, no built-in phone mail app, no calendar sync into an outside client, and no AI or automation layer connecting over IMAP or JMAP.

For a warehouse or field team that lives in webmail, that is a real saving and the tier exists for exactly them. For anyone who has used a desktop mail client for a decade, it is a migration that fails on day one.

One exception matters before you write Basic off. A Basic user can still send and receive at your organisation's custom domain, provided the account administrator is on Standard or Professional. Basic does not strand somebody on a generic address; it means their seat cannot own a domain or reach an outside app.

Does Fastmail charge extra for a custom domain?#

Not for connecting one. Standard and Professional include custom domain support, and Fastmail states you can add up to 100 domains to an account at no extra cost. Basic is the exception, because a Basic seat does not include a custom domain of its own.

What you still pay separately is the domain registration itself. That is a registrar cost, it recurs annually, and it exists no matter who hosts your mail. Fastmail can register one on your behalf from Settings, an option it says is open to paid customers after the first week and not available on Basic.

Fastmail storage limits by plan, and who actually needs more#

Because Fastmail publishes storage per user rather than as a shared pool, one archivist with fifteen years of attachments pushes only their own seat up a tier rather than the whole account.

As of August 2026, mail, calendar and contacts storage runs 5 GB per user on Basic, 50 GB on Standard and 100 GB on Professional. File storage is a separate allowance of 1 GB, 10 GB and 50 GB respectively, so heavy file use does not eat into mailbox capacity.

The practical read: 50 GB is a great deal of plain email. Teams that exceed it are usually storing large attachments in the mailbox rather than in a file store, and the fix is a habit more often than a tier. Professional earns its place through the retention archive, not the gigabytes.

Worked example: a nine-person agency#

Take a nine-person agency: three partners, four account managers, and two part-time contractors who only check mail in a browser. They also want info@, support@ and billing@ working from day one.

The naive maths is nine seats at one tier. The accurate maths starts by removing the addresses that are not people. Those three role addresses are shared, included on every tier, and consume no seat. Headcount and seat count are already different numbers.

Then split by app access. The partners and account managers use desktop or phone mail clients and want Masked Email, so they need Standard. The contractors work entirely in webmail, so Basic covers them and they still send from the company domain. One partner handles contracts and wants the tamper-proof archive, so that seat goes to Professional.

The result is a mixed account rather than a uniform one, and that is a materially different bill from nine identical seats. The difference came from two decisions, not from negotiating.

Annual billing and the commitment ladder#

Fastmail offers monthly billing plus 12-, 24- and 36-month terms, with the discount increasing as the term lengthens. As of August 2026 that ladder applies across the business tiers.

The trade-off is sharper for email than for most software. Email is the hardest thing in your stack to move later, so a long term carries less switching risk here than it would for a CRM. That same stickiness is why you trial with real mail and real clients first.

A sensible sequence: trial the tier you think you need, run one month billed monthly with the team migrated, then commit longer. The multi-year saving is smaller than the cost of learning in month two that half your seats need app access.

Is Fastmail cheaper than Google Workspace?#

On the seat alone, usually. As a total decision, that is the wrong place to stop.

Fastmail sells mail, calendar, contacts and a modest file allowance. Google Workspace sells those plus Docs, Sheets, Slides, Drive at suite scale, Meet, and a compliance layer built for larger organisations. If your team already pays for documents and video elsewhere, Fastmail's seat is cheaper and you give up nothing. If your team writes in Google Docs all day, cancelling Workspace to save on email means re-buying the documents somewhere else.

There is also a capability gap worth naming plainly. Fastmail does not publish SSO or SAML sign-on for business accounts, and its own help documentation states it is not HIPAA compliant, which means no signed BAA. If your security review requires either, Fastmail is out on capability rather than price. Fastmail does offer a GDPR data processing agreement to any customer who asks.

The comparison that holds up is Fastmail against another mail host such as Zoho Mail, Proton or Migadu, not Fastmail against a suite.

What Fastmail does not include#

None of these are defects, because Fastmail is priced as an email host rather than a suite. They only become problems when the purchase was framed as a suite replacement.

• Documents, spreadsheets and presentations. There is no Fastmail equivalent of Docs or Office.
• Video conferencing and team chat.
• Published SSO or SAML sign-on for business accounts.
• HIPAA compliance or a business associate agreement, per Fastmail's own documentation.
• A permanent free tier. There is a trial of up to 30 days, then it is paid.
• Third-party app access on Basic seats, and the retention archive below Professional.

Red flags to check before you commit#

Four things are worth confirming before you sign, because each is cheap to fix now and expensive to fix after a migration.

• Legacy plan billing. Accounts predating the April 2024 plan change sit on legacy plans and are migrating over time. Legacy business accounts are billed separately for retention archive storage per gigabyte, and Fastmail notes that billing continues while the data exists even after the feature is switched off.
• Retention is not retroactive. The archive captures only mail sent and received after an admin enables it for that user, so switching it on the week your lawyer asks for records does not produce the records.
• Seat creep. Every hire is a new seat at their tier. Model the bill at the headcount you expect in a year, not today's.
• App access audit. Covered above, and the single item most likely to break a migration.

What we'd pick, and who should pick something else#

For most small businesses, Standard is the right default, and the tier mix is where the actual saving lives. Buy Standard for everyone who touches a mail client, Basic only for people you have confirmed live in webmail, and Professional only for seats that genuinely need the retention archive.

Fastmail is the right pick if you want mail hosting that is fast, private, standards-based and priced as email rather than a suite, and if your compliance needs stop short of SSO and a signed BAA. Go elsewhere if you need documents and video bundled, or if a security review mandates SAML: Google Workspace and Microsoft 365 own that ground and it is not close.

Where AI Emaily fits, and we build AI Emaily, so weigh this accordingly. We are not mail hosting and do not replace a Fastmail seat. We are the client and the AI layer on top of one: an inbox that triages, drafts in a voice you set through a Personal Context brain and per-client profiles, and closes loops, with approve-before-send, undo and an audit trail on every agent action.

So if your problem is the per-user hosting bill, we do not solve it and the tier mix above does. If your problem is that seven people each spend two hours a day inside those mailboxes, that is the job we do.

The limits, plainly. We connect over IMAP and JMAP, so a Fastmail Basic seat cannot use us at all and Standard is the floor. We are a 7-day free trial on Pro and Autopilot rather than a free tier, so our trial window and Fastmail's do not line up. Run Fastmail's first, then add us once the mail is flowing.