Fastmail for Families and Small Teams: How Shared Accounts Work

Fastmail sells two kinds of multi-person account: a Family plan for households and Business plans for companies. Both put one person in charge of billing and let everyone else keep a separate, private mailbox on a shared domain.

Neither one is a shared inbox in the Front or Missive sense. If five people need to see and claim the same support@ thread, Fastmail gets you most of the way there with shared folders, but the last mile is manual. This post covers what's actually included, how to set it up, and where that gap shows up.

How does the Fastmail family plan actually work?#

The Family plan is a single subscription that supports up to 6 separate users, each with their own login, password and mailbox. It is not an add-on to an individual plan — it's a standalone tier priced for the household, not per seat.

As of September 2026, Fastmail lists Family at roughly $132/year (about $11/month billed annually), with each of the up to 6 users getting their own storage allotment. Check Fastmail's own pricing page before you buy — plan pricing and storage figures change, and this post won't stay current with them.

The person who signs up becomes the account administrator by default. They pay the bill, add and remove users, and can hand admin rights to someone else if they want shared control. Every other user gets a private mailbox that the admin cannot read unless privacy restrictions are turned off for that account.

• One payment covers everyone on the plan — no per-person invoices to chase down
• Each user's mail, contacts and calendar are private by default, separate from the admin's
• Users can share a family domain, so addresses look like [email protected] instead of [email protected]
• Shared or private calendars and address books are available per user, your choice

Before you start#

A few things to sort out before you touch the admin panel, because they're harder to undo than to plan for up front.

• Decide who the account administrator is. That person's card is on file and their judgment call it is when someone needs to be removed.
• If you want a shared domain (yourfamily.com or yourcompany.com instead of a fastmail.com address), have DNS access ready — you'll add the domain and verify it with a TXT record before anyone can use it.
• Pick a plan tier that actually matches how many people need mailboxes. Family tops out at 6 users; a growing team needs a Business plan instead, since Business has no published user cap.
• If this is a business account, decide now which users need admin rights. Admin controls include disabling a user's login, resetting their password, and reading their mail unless you exempt them — decide who should have that power before you hand it out.

How do I add a user to Fastmail?#

Adding a person to either plan type goes through the same admin screen. The steps below apply to Family and to Business accounts alike.

1. 1

   Open Settings → Users & Sharing

   Sign in as the account administrator and go to the Users & Sharing screen. This is where every user on the account is listed and managed.

2. 2

   Click New user

   Set a username, display name, and an initial password. Fastmail can generate a random password for you, which the new user changes on first login.

3. 3

   Assign a domain and address

   If you've already added a shared custom domain, pick it here so the new mailbox is [email protected] instead of a default fastmail.com address.

4. 4

   Set storage and plan tier (Business only)

   On Business accounts, choose which tier (Basic, Standard or Professional) this user's mailbox runs on — you can mix tiers on one account, and the invoice reflects each user's tier.

5. 5

   Decide on admin rights

   Scroll to the bottom of the user's settings page and check "Admin: allow this user to manage this account" only if they should be able to add, remove, or reconfigure other users and billing.

6. 6

   Set up shared folders, calendars or contacts

   If the new user needs to see a shared folder or calendar, share it from the owner's account settings — sharing isn't automatic just because two users are on the same billing account.

Fastmail shared folders setup: what you get and what you don't#

Any user can share a mail folder, calendar or address book with specific other users on the account, or with people outside it if they have their own Fastmail login. Shared folders show up as a distinct item in the recipient's folder list — they don't merge into a single unified view the way a real shared inbox would.

That distinction matters for support or sales teams. A shared folder is closer to a read/write bulletin board than a queue: nobody gets automatic assignment, there's no built-in "claimed by" state, and there's no SLA timer. Two people can reply to the same thread at the same time and nobody is warned.

Zoom out from any single folder and the account structure looks the same whether it's a Family plan or a Business plan: one shared domain at the top, with each user's mailbox, storage and login sitting underneath it as a separate, self-contained block.

Platform differences: Fastmail vs. Google Workspace for a small team#

If you're weighing Fastmail's Business plans against Google Workspace or Microsoft 365 for a small team, the honest comparison is about what each one is built to do, not which one is "better" in the abstract.

What to do when a shared setup doesn't work#

Most Fastmail family and team problems trace back to one of three causes: a DNS record that hasn't propagated, a sharing permission nobody set, or a plan mismatch between what the account supports and what the team expects.

• New domain won't verify: DNS changes can take up to 48 hours to propagate, though it's usually much faster. Recheck the exact TXT record value against what Fastmail's domain setup screen shows — a copy-paste truncation is the most common cause.
• A user can't see a shared folder: sharing has to be granted explicitly per folder, per user. Being on the same billing account does not share anything automatically.
• Two people keep double-replying to the same thread: this isn't a bug, it's the shared-folder model working as designed. If it's a recurring problem, that's a signal you need thread-claiming behavior a shared folder doesn't provide.
• You've hit the 6-user cap on Family: there's no way to add a 7th user to a Family plan. Move the account to Business, which prices per user instead of per household.
• Admin removed the wrong user: user deletion is permanent and immediately wipes that person's mail, contacts and calendar. Fastmail's own docs are explicit that this can't be reversed, so confirm the username twice before you click delete.

A faster way to run threads across a shared mailbox#

Shared folders solve who can see a message. They don't solve who's supposed to act on it, or what happens after three people have already looked at a thread and nobody has replied. That's a triage and follow-up problem, and it's a different problem than storage or permissions.

AI Emaily connects to a Fastmail mailbox — family or business, shared folder or not — and layers autonomous triage on top of what's already there: drafts get written in your voice from a Personal Context brain you set up, replies wait for your approval in Copilot mode before anything sends, and every action is undoable and logged in an audit trail.

It doesn't replace Fastmail's account structure; it works with the mailbox you already have, on any provider, so switching shared-inbox habits doesn't mean switching email providers. We build AI Emaily, and it's worth trying against your actual shared inbox rather than taking that on faith — a 7-day free trial covers it.