How to Set Up Fastmail for the First Time (First-Week Guide)

A new Fastmail account works out of the box — mail arrives, search works, the spam filter is already on. But the settings you skip in week one are the ones that cost you rework in month three: a folder structure you have to rebuild, a missing rule that lets the same newsletter through fifty times, an app password you didn't generate before your phone's mail app locked you out.

This is the order that avoids that. Five things, roughly 20 minutes: identities, folders, rules, spam level, app passwords. Two-step verification is worth doing too, but it's independent of the rest, so it's last.

Before you start: what Fastmail sets up for you automatically#

Every new account already has a working Inbox, and Fastmail auto-creates the standard system folders — Drafts, Sent, Trash, Spam, and Archive — the first time you use them. You don't need to create these; they exist so IMAP clients (Apple Mail, Outlook, Thunderbird) can map to them by convention.

Spam protection is also on by default at the Standard level the moment you sign up or upgrade to a paid plan. That's a reasonable starting point for most people — the changes below are about tuning it to your mail, not turning it on.

• Inbox, Drafts, Sent, Trash, Spam, Archive — created automatically
• Spam protection — on, Standard level, by default
• One identity (your primary address) — ready to send from immediately

Step 1: Confirm your identity, and add more if you send from multiple addresses#

1. 1

   Check your default sending address

   Go to Settings → Mail preferences → Compose. The Default address field controls which address appears in the From line on a new message. If you only have one address, this is already set correctly.

2. 2

   Add a second address if you need one

   Settings → My email addresses → Add address lets you create an additional alias on your domain (or a masked address) that can send and receive independently, without creating a second Fastmail account.

3. 3

   Set a display name per address

   Each address can carry its own display name — useful if one address is personal and another is for a side project or a shared team inbox.

Step 2: Build folders around how you actually triage mail, not how Gmail trained you#

Fastmail's system folders cover the mechanics — sent, deleted, junk. They don't cover triage. If you're coming from Gmail, resist recreating a dozen labels on day one; folders in Fastmail are exclusive (a message lives in one folder, not many), which is a different mental model than Gmail's labels.

Start with three or four purpose-built folders and add more only when a real backlog justifies it: Receipts, Waiting on Reply, and a Reference folder for things you'll search for later but never triage again. Archive already exists for everything else — the folder Inbox Zero users lean on for mail that doesn't need a label.

Step 3: Write one rule, on the sender that's already annoying you#

Rules in Fastmail are two parts: conditions a message must match, and actions applied to matches. You can build one from Settings → Filters & Rules → Create rule, or faster — open a message from the sender you want to handle, use the More menu, and choose Add Rule from Message. Fastmail pre-fills the condition from that message's sender, subject, or mailing-list header.

Don't try to build your full rule set on day one. Pick the one sender or category that's already cluttering your inbox — a notification digest, a recurring newsletter — and file it automatically. Everything else, add a rule for it the next time it annoys you.

Step 4: Set your spam protection level#

Spam protection lives at Settings → Filters & Rules → Spam protection, under Protection level. There are four options: Off, Standard, Aggressive, and Custom. Standard is the default and the right starting point for most inboxes — Fastmail is deliberately conservative here, because a wrongly-filed real message is worse for most people than an occasional spam message reaching the inbox.

Switch to Aggressive only if Standard is letting through a lot of junk after a few weeks of real use, not on day one — you don't have enough signal yet to know which level you need.

Step 5: Generate an app password for any client that isn't OAuth-native#

If you're connecting a third-party mail app that authenticates over IMAP/SMTP rather than modern OAuth — some desktop clients, some older devices — it will ask for a password that isn't your account login. That's an app password, generated at Settings → Privacy & Security → Connected apps & API tokens → Manage app passwords and access → New app password.

Name each one after the app or device it's for, so you can tell what to revoke later without guessing. Fastmail also lets you scope what an app password can access — Mail, Contacts & Calendars is the default and usually the right choice.

Platform differences: what setup looks like per client#

The settings above live in Fastmail's own web interface regardless of which app you actually read mail in. What differs by platform is how that app connects — and whether it needs the app password from Step 5 at all.

What to do when it doesn't work#

The two things that break most often in week one are both password-related, not server-related.

• Client rejects your login with 'incorrect password' — you're using your account password instead of an app password. Any client connecting over IMAP/SMTP needs the app password from Step 5, not your login credentials.
• A real message lands in Spam — open it from the Spam folder and mark it 'not spam.' Fastmail's filter uses your corrections as a signal, so this is part of tuning Standard-level protection, not a workaround.
• A rule isn't firing — check condition order. Rules run in sequence, and an earlier rule with a broader match (or a 'stop processing' action) can prevent a later, more specific rule from ever being evaluated.
• Two-step verification locks you out — this is why Fastmail requires a recovery phone before you can enable it. If you lose the device, use the recovery method you set at enrollment, not the support ticket queue as your first move.

A faster way: doing this continuously, not just in week one#

The five steps above get a Fastmail account into good shape once. The work that actually keeps an inbox organized is repeating steps 2 and 3 — noticing a new sender that deserves a folder, writing the rule for it — every week, indefinitely. Most people do it for the first month and then stop.

We build AI Emaily, an AI-native email client that connects to Fastmail over IMAP and keeps doing that triage work after the setup checklist is finished: it reads incoming mail against rules and a Context brain you control, files and drafts continuously, and asks before it sends anything. It doesn't replace the folders and rules you just built — it's what running them looks like when you're not the one doing it every day.