Fastmail Email Settings: IMAP, SMTP, POP3 and App Password

Q: What are the Fastmail IMAP settings?

Use imap.fastmail.com on port 993 with SSL/TLS. Your username is the full email address, including a custom domain if you use one. The password must be an app password . The complete table sits in the IMAP settings section .

Quick answer: the Fastmail IMAP server is imap.fastmail.com on port 993 with SSL/TLS. The outgoing server is smtp.fastmail.com on port 465 with SSL or 587 with STARTTLS. The POP3 server is pop.fastmail.com on port 995 with SSL. Your username is the full email address. The password has to be an app password. Your normal Fastmail password will not work in a mail client. Neither will your two step verification password. One thing to check before any of it: the Basic plan carries no IMAP access at all.

Every value here is proven against live IMAP and SMTP connections made by Univik email software. We have built email backup and converter tools since 2013, so these servers are ones we connect to daily. See what changed →

What Changed Recently#

Fastmail keeps its server addresses steady and puts its restrictions in the account rules instead. These are the ones that decide whether a client connects.

Latest update

Your plan decides whether IMAP exists for you. Fastmail Basic carries no IMAP, SMTP, CalDAV or CardDAV. Anyone on that tier is limited to webmail and the official app. Moving down to Basic from a higher plan also switches off every app password you already made, which breaks working clients without warning.

Earlier change

App passwords are the only accepted credential. Fastmail refuses both your account password and your two step verification password in any external client. There is no setting that changes this.

Earlier change

JMAP sits alongside IMAP. Fastmail helped author JMAP as a modern replacement for IMAP and supports both. IMAP is not going anywhere, so the settings here stay valid, though a JMAP capable client will feel quicker.

Current status: on any plan above Basic, IMAP, POP and SMTP all work normally with an app password scoped to Mail. No toggle needs switching on anywhere.

Before You Begin#

Two checks come first. Miss either one and your mail app will refuse the connection even with every server value on this page entered correctly.

1. Check which plan you are on

Fastmail Basic includes no IMAP, no SMTP, no CalDAV and no CardDAV. On that plan there is nothing to configure, because outside clients cannot connect at all.

Where: Plan check below →

2. Create an app password

Fastmail rejects your account password in every external client. It rejects your two step verification password too. An app password is the only credential that works here.

Where: App password steps below →

About Fastmail Mail#

Fastmail is a paid, ad-free mail service run by Fastmail Pty Ltd from Melbourne, Australia. It has been running since 1999, which makes it one of the oldest independent mail hosts still operating.

Fastmail funds itself on subscriptions rather than advertising, so there is no free tier to fall back on, only a 30 day trial. Opera Software bought the company in 2010, then the staff bought it back in 2013 and it has been independent since. It went on to acquire Pobox and helped author JMAP, the modern protocol built as a successor to IMAP. Two things make connecting a client here different from most providers. Your account password is refused in every external app without exception. The cheapest plan removes client access altogether.

Service Name	Fastmail Mail
Owned By	Fastmail Pty Ltd, an independent Australian company
Launched	1999, in Melbourne
Email Domains	`@fastmail.com`, `@fastmail.fm`, your own custom domain, plus a long list of Fastmail owned domains
Webmail URL	app.fastmail.com
Protocols Supported	IMAP, POP3, SMTP, JMAP, CalDAV, CardDAV. Not on Basic
App Password Needed	Yes, always, for every client on every plan that allows one
Free Storage	None. Paid only, with a 30 day trial and no card required

One server set, whatever your address: @fastmail.com, @fastmail.fm, one of Fastmail's other owned domains or your own custom domain all connect to the same three hosts on this page. Hosting your own domain at Fastmail changes your username and nothing else. That is worth knowing, because plenty of providers hand custom domain customers a different server name.

Three hosts cover every kind of Fastmail address.

Fastmail Webmail Login#

Webmail keeps working no matter what your mail app is doing. These are the pages Fastmail actually runs:

Webmail

app.fastmail.com

Account Security

fastmail.com/settings

Password Recovery

fastmail.help

Watch out for fake support pages. A number of pages that rank for email settings put a phone number on screen and invite you to ring it for paid setup help. Neither Fastmail nor Univik will ever ask you to phone anyone to enter a server address. Every value you need is here at no cost.

Which Fastmail Plan Are You On?#

Fastmail is the rare provider where the plan decides whether any of this works. There is no toggle to find and nothing to enable. Client access is either included with your plan or absent from it.

Basic plan. No IMAP, no POP, no SMTP, no CalDAV and no CardDAV. Fastmail states this plainly in its own documentation. Webmail in a browser and the official Fastmail app are your only options, so no value on this page applies to you.
Individual, Duo and Family plans. Client access is included. Everything below works.
Business Standard and Professional. Client access included, along with custom domains.
Not sure which you have? Open Settings in webmail and look at your subscription. If the app password screen refuses to let you create one, you are on Basic.

Check this before anything else. On Basic there is nothing on this page you can use.

Downgrading to Basic breaks a working setup. Fastmail disables your existing app passwords the moment you move down to a Basic plan. Outlook and Apple Mail keep the saved password, then start failing to sign in, which reads exactly like a server fault rather than a billing change.

A subscription change with no obvious connection to the symptom.

Fastmail IMAP Settings#

IMAP is the incoming protocol to reach for. Mail stays on the Fastmail server, so every device you own looks at one identical inbox.

IMAP Server	`imap.fastmail.com`
Port	`993`
Encryption	SSL/TLS (required)
Username	Your full email address, including `@fastmail.com`
Password	An app password. Your account password is rejected here
Authentication	Required

Fastmail POP3 Settings#

POP3 pulls mail down to one machine. It suits a single computer holding a local copy and little else. Undecided? The comparison sits below.

POP3 Server	`pop.fastmail.com`
Port	`995`
Encryption	SSL/TLS (required)
Username	Your full email address
Password	The same app password works for POP as for IMAP

POP3 is the wrong choice on Fastmail. Fastmail calls POP an older standard that IMAP has largely replaced. Server side rules are one of the reasons people pay for Fastmail, so it is a shame to throw away the folder structure those rules build. Some clients also strip mail off the server once downloaded, so tick "leave a copy on the server" if you use it anyway.

Fastmail SMTP Settings#

Encrypted ports only: Fastmail takes encrypted connections and nothing else. The old plain ports 143 for IMAP and 110 for POP3 do not connect. If your mail app filled one of those in by itself, correct the port and switch encryption on.

SMTP carries outgoing mail. If messages arrive but nothing sends, look here first. Fastmail recommends port 465 with SSL, which is the reverse of what many providers suggest, though 587 with STARTTLS works too.

SMTP Server	`smtp.fastmail.com`
Port (SSL)	`465`
Port (STARTTLS)	`587`
Encryption	SSL or STARTTLS (required)
Username	Your full email address
Password	The same app password as incoming, provided its access scope covers Mail
Authentication	Required. In Outlook this is the outgoing server authentication checkbox.

Check Fastmail IMAP Settings Online#

You don't need to download anything to check Fastmail IMAP settings online. This page is the lookup: every value is verified, current and copyable straight from your browser. Not sure your address uses Fastmail servers? Type it below and find out instantly.

Does my email address use these settings?

Runs in your browser only. Your address is never sent anywhere or stored.

Want to verify the account itself before configuring an app? Sign in at Fastmail webmail, which confirms your address and password work, then confirm an app password exists. If both pass, any email app connects with the tables above.

Look Up IMAP Settings for Any Email Domain#

This page covers Fastmail. For every other address, work email on a company domain included, we run a free online lookup database: imapsettings.com.

imapsettings.com

Complete email settings database, by Univik

Check IMAP settings online →

Enter any email address and get the incoming and outgoing server settings for that domain in 1 step:

Incoming server: hostname, port, SSL/TLS and username format

Outgoing server: SMTP hostname, port and encryption

The address is read locally to identify the domain. It goes nowhere and is kept nowhere.

Fastmail App Passwords and Access Scopes#

Fastmail takes a harder line than most providers here. Only an app password authenticates an outside client. Here is what each credential actually opens.

Where you sign in	Account password	2FA password	App password
Fastmail webmail and official apps	✓ Works	✓ Works	Not needed
Outlook, Apple Mail, Thunderbird	✗ Rejected	✗ Rejected	✓ Required
Phone mail apps set up by hand	✗ Rejected	✗ Rejected	✓ Required
Calendar and contacts apps (CalDAV, CardDAV)	✗ Rejected	✗ Rejected	✓ Required

Two of these three are refused, which is where most Fastmail setups stall.

How to Create a Fastmail App Password

Sign in to Fastmail webmail on a computer, then open Settings → Privacy & Security.
Find the connected apps section and choose to manage app passwords. Older help pages call this tab Integrations, so you may see either name.
Click New app password. Fastmail may ask for your account password to confirm it is you.
Name it after the device, not the person, for example "Outlook on the work laptop". You will thank yourself when you need to revoke one.
Leave the access scope on Mail, Contacts & Calendars unless you know otherwise, then generate it and paste the password into your client. Fastmail shows it once.

The scope is the part people get wrong: an app password carries a permission scope. Picking the wrong one produces a failure that looks nothing like a permissions problem. A password scoped to Files rather than Mail will sit there refusing to send or receive while the server name and port are perfect. Fastmail shows the scope in brackets beside each app password name, so open Settings → Privacy & Security and read it there before you start changing ports.

The scope is chosen once and rarely revisited, so choose it deliberately.

Set Up Fastmail in Email Clients#

Every client wants the same three hosts and the same app password. Only the menu names change. Pick your app:

Outlook Apple Mail iPhone and iPad Android Thunderbird

The same seven values go into every client. Only the menus differ.

Outlook (Windows and Mac)

In Outlook go to File, then Add Account. New Outlook hides the same option under Settings, then Accounts.
Enter your Fastmail address, open Advanced options and check "Let me set up my account manually".
Choose IMAP and enter imap.fastmail.com port 993 (SSL) and smtp.fastmail.com port 587 (STARTTLS).
Paste your app password when Outlook asks. Your account password will be turned away.
Send yourself a test message once setup finishes, which proves sending and receiving in one go.

Apple Mail (macOS)

In Apple Mail go to Settings, open Accounts, then Add Account.
Choose Other Mail Account. Apple does not list Fastmail among its built in providers.
Enter your name, address and app password, then continue.
Should it ask for server names, copy them from the IMAP and SMTP tables higher up.
Turn off "Automatically detect and preserve server settings" for this account. Apple Mail otherwise overwrites what you typed with its own guesses, which is a known headache on Fastmail.

iPhone and iPad

On iOS open Settings, then Apps, then Mail, then Mail Accounts, then Add Account.
Tap Other → Add Mail Account. iOS carries no Fastmail entry in its provider list.
Enter your details with the app password, then tap Next.
Leave IMAP chosen, filling in the incoming and outgoing hosts should iOS prompt for them.
Tap Save, then give iOS a moment to check the account works.

Android

Open whichever mail app you use on Android, then choose Add account.
Pick Other, then IMAP, since Fastmail will not appear in the provider list.
Enter your address and app password. If auto setup fails, pick Manual setup.
Enter the servers: imap.fastmail.com 993 SSL incoming, smtp.fastmail.com 465 SSL outgoing.
Complete setup, then pull down on the inbox to start the first sync.

Thunderbird

In Thunderbird open Account Settings, then Account Actions, then Add Mail Account.
Enter your name, address and app password, then select Continue.
Thunderbird finds the Fastmail servers on its own in most cases. Check that IMAP is the chosen option.
Where detection comes up short, switch to Configure manually and type the values from the tables.
Choose Done, at which point your folders begin syncing.

Sending From an Alias in Your Mail App#

Aliases are one of the reasons people pay for Fastmail, though they trip up almost everyone the first time. Receiving on an alias works from the moment you create it. Sending from that same address is a separate permission, so a perfectly configured client will still refuse to send until you grant it.

Two different permissions on one address, which is why the error looks so odd.

What you see	Why	What to do
5.7.1 Not authorised to send from this header address	The From address is not an alias on your account	Add it under Settings → My email addresses. Fastmail blocks this by default to stop people spoofing addresses through its servers.
To send as this address you must first verify that you own it	The address belongs somewhere else	Use the Fix it button beside the address. You either prove you receive mail there or point Fastmail at that provider's own SMTP server, which Fastmail recommends for deliverability.
Recipient address rejected: User unknown in virtual mailbox table	The alias is brand new	Wait. Fastmail says an alias can take up to 15 minutes to take effect. Rebuilding it restarts the clock rather than fixing anything.

Older guides send you to a screen that no longer exists. Fastmail used to split these into aliases for receiving and sending identities for sending, each configured separately. The interface now uses one alias that does both. Any walkthrough pointing you at a Sending Identities screen was written before that change, so look under Settings → My email addresses instead.

Fastmail Webmail Settings#

The values above connect your apps. This next group governs how the mailbox itself behaves. All of it lives in webmail under Settings.

Signature

Settings has its own signature area, with a separate signature possible per sending identity. Anything you save there applies to webmail. Outlook and Apple Mail keep their own, so expect to write it twice.

Vacation Auto Reply

Fastmail calls this the vacation responder. Give it a start date and an end date so it switches itself off. It runs on the server, so replies keep going out with every device of yours powered down.

Filters and Folders

Rules run on the server, sorting mail before any device fetches it. Fastmail builds these on Sieve. It will let you edit the Sieve directly once the rule builder runs out of room. A rule inside Outlook only fires while Outlook is open.

Spam and Blocked Senders

Block single addresses or whole domains from the spam area. Fastmail also offers Masked Email, which hands out a throwaway address per signup so you can kill one off without touching your real one.

Fastmail POP3 vs IMAP#

Feature	IMAP	POP3
Where mail lives	On the Fastmail server	Downloaded to 1 device
Multiple devices	✅ Everything stays in sync	❌ Each device sees different mail
Sent and deleted mail	✅ Synced everywhere	⚠️ Stays only on that device
Offline reading	⚠️ Cached mail only	✅ Full local copy
Server storage used	Yes, counts against your quota	Can be freed after download
Best for	Phone + computer, everyday use	Single PC, local archives

Our verdict: use IMAP. Fastmail itself steers people away from POP. If your client speaks JMAP, that is newer again. For a permanent offline archive, a backup tool does the job properly rather than POP3 pretending to.

Fastmail Plan and Storage Limits#

Fastmail sets these by plan rather than publishing one universal figure, so check your own subscription for the exact numbers. What matters most for setting up a client is the top row.

Client access (IMAP, POP, SMTP)	Included on Individual, Duo, Family, Standard and Professional. Absent on Basic
Mailbox storage	Set by plan. Basic sits around 6 GB in total, while Standard and Individual run to roughly 60 GB per user
Free tier	None. Fastmail is subscription funded, with a 30 day trial that needs no card
Aliases and domains	Hundreds of aliases on one mailbox, plus Masked Email for throwaway addresses. Up to 100 domains can sit in a single account
Sending limits	Set per plan and aimed at personal and small business use. Fastmail does not publish one figure that covers every subscription
Going over storage	Fastmail soft bounces incoming mail for roughly a week rather than billing you for the overage, so clear space quickly

Troubleshooting Fastmail Connections#

Almost every Fastmail connection failure traces back to one of three things: the plan, the password type or the access scope. Find your symptom below.

Error you see	What it means	Fix
Password error, though the password is right	You entered your account password or your 2FA password	Neither works in a client. Create an app password and paste that instead.
Cannot create an app password at all	You are on a Basic plan	Basic excludes IMAP, SMTP, CalDAV and CardDAV. See which plan you are on. Webmail and the Fastmail app still work normally.
Signs in but will not send or receive	The app password has the wrong access scope	Check the scope in brackets beside its name in Settings → Privacy & Security. It needs Mail, not Files.
Cannot connect to server	Wrong port or encryption	Check IMAP 993 SSL and SMTP 465 or 587. Antivirus software and VPN apps block these ports more often than people expect.
Password keeps being asked	Saved credential is not an app password	Remove the stored password and enter an app password. If it was working until recently, check whether the plan was downgraded to Basic.
Refuses to send from one of your aliases	The From address is not authorised on the account	See sending from an alias above. Receiving on an alias does not grant permission to send from it.
Messages stuck in Outbox	SMTP authentication is off	Switch on the outgoing authentication option, giving it the same credentials as incoming.

Reader Reported Fixes

Apple Mail quietly rewriting your server settings. Someone enters the Fastmail hosts correctly, the account works, then it breaks days later with no change made. Apple Mail had re-detected the settings and replaced them. Turning off "Automatically detect and preserve server settings" for that account stops it happening again.

A working setup that died after a billing change. Moving down to a Basic plan disables every app password on the account. The mail app keeps the saved credential and keeps failing, which points suspicion at the server rather than the subscription. Moving back up to a plan with client access restores it, though you will need to create fresh app passwords.

Moving To or From Fastmail?#

Coming in from another provider? Fastmail has its own import that pulls mail across over IMAP, so you need the other side's server settings rather than these. Bring your custom domain with you and the values on this page do not change at all.

Moving mail out? Use IMAP on both ends. On the Fastmail side that means the hosts above with an app password scoped to Mail, because a migration tool is another external client as far as Fastmail is concerned.

Cancelling the subscription? Back up the mailbox first. This is a paid service with no free tier to fall back to, so access ends when billing does. Take your copy while you can still sign in.

Taking your mail to a new account? The Univik Email Migration Tool copies every folder from the old account to the new one. Enter the IMAP settings from this page for the Fastmail side and your new provider's settings for the other.

Rather not do it yourself? The Email Migration Services team scopes the move, carries it out, then checks every folder landed.

Use These Settings in Univik Email Backup#

The same IMAP settings above let you download your complete Fastmail mailbox to your computer. Univik Email Backup writes the lot to PST, MBOX, EML or PDF, which stay yours after the subscription lapses.

Install Univik Email Backup on a Windows machine.
Choose Fastmail as the source. Where it is absent from the list, pick the generic IMAP option.
Sign in with your full email address and an app password scoped to Mail. A backup tool is an external client, so your account password fails here too.
If the tool asks for server details, use imap.fastmail.com with port 993 and SSL from the IMAP table above.
Choose an output format and destination folder, then begin. A big mailbox keeps downloading while you get on with something else.

Why back up before switching providers: POP3 only grabs the inbox and vacation replies to a closed account bounce. Pulling the mailbox over IMAP preserves folders, attachments and original dates in files that open in any mail app. Switching accounts rather than archiving? The email migration tool moves mail straight across without an export step.

Email Settings Glossary#

IMAP

Internet Message Access Protocol. Reads mail that stays on the server, so all your devices see the same inbox, folders and read status.

POP3

Post Office Protocol version 3. Downloads mail to 1 device and can remove it from the server. Older method, still useful for local archives.

SMTP

Simple Mail Transfer Protocol. Sends your outgoing mail. Every account needs it next to IMAP or POP3, which only receive.

SSL / TLS / STARTTLS

Encryption for the connection. SSL/TLS encrypts from the start (ports 993, 995, 465). STARTTLS upgrades a plain connection (port 587).

App Password

A separate code standing in for your real password inside an app. Safer, because revoking one app leaves your main password alone. On Fastmail each app password also carries an access scope deciding what it may reach.

OAuth

Signing in through the provider's own window rather than typing a password into the app. Fastmail takes a different route, using scoped app passwords, so you will not see an OAuth window when adding a Fastmail account by hand.

How We Verify These Settings#

Univik has built email backup, migration and converter software since 2013. Our tools sign in to Fastmail over IMAP and SMTP every day for thousands of users, so a changed server, port or login rule shows up in our connection logs before most guides notice it.

Every value on this page is confirmed with 3 checks: a live IMAP and SMTP connection from Univik Email Backup, a comparison against Fastmail's own help documentation and a fresh app password created through the current settings flow. Any announcement from Fastmail triggers a recheck. We revisit the page quarterly regardless.

Spotted something that no longer matches your Fastmail screen? Let us know. We retest, correct the page, then record it in what changed recently.

Help & Support

Frequently Asked Questions

Use imap.fastmail.com on port 993 with SSL/TLS. Your username is the full email address, including a custom domain if you use one. The password must be an app password. The complete table sits in the IMAP settings section.

Because Fastmail refuses that password by design. Outside clients take an app password and nothing else, not your account password and not your two step verification password. Create an app password and paste that in. If the screen will not let you create one, you are on a Basic plan, which has no client access at all.

IMAP for almost everyone. It keeps your phone, computer and webmail in sync. POP3 fits only a single computer setup where you want a local download. Full comparison here.

Yes. On Fastmail that holds for your address too. The same three hosts serve @fastmail.com addresses, Fastmail's other domains and your own custom domain. Only the menus move around, which is what the client setup guides handle.

No. Fastmail displays it once and never again. Delete that entry under Settings → Privacy & Security, then create a replacement. Your other app passwords keep working, which is the reason to name each one after its device.

Yes. An app password is safer than your real one, since it reaches only what its scope allows and can be revoked on its own. Keep two step verification on for your account, then look through the app password list occasionally and delete any belonging to a device you no longer use.

An IMAP client pulls mail down as it syncs, though a dedicated backup tool works faster and writes standard files that open anywhere. See how to back up your Fastmail mailbox. Sitting on an old export in some other format? An email converter turns it into PST, PDF or whatever your next app reads.

On Fastmail there are two usual suspects. A plan downgrade to Basic disables every app password on the account. Separately, Apple Mail can silently re-detect and overwrite server settings you entered by hand. Both look like a server problem. Check what changed recently and the reader reported fixes.

An email migration tool copies mail directly between the 2 accounts over IMAP. You need the Fastmail IMAP settings and an app password scoped to Mail for this side, plus the same details for the destination account. Every folder, label and date stays intact.

Where the stakes are high or the account count is large, our managed email migration service takes the whole thing off your hands.

Other Email Provider Settings

Gmail Settings Outlook.com Settings Yahoo Mail Settings AOL Mail Settings iCloud Mail Settings Comcast Settings

Summary: Fastmail Settings at a Glance

IMAP: imap.fastmail.com, port 993, SSL/TLS
POP3: pop.fastmail.com, port 995, SSL/TLS
SMTP: smtp.fastmail.com, port 465 (SSL) or 587
Username is always your full email address

App password always required, never your account password
Give it the Mail access scope
Basic plan has no IMAP at all
Custom domains use the same servers