Fastmail SMTP, IMAP and POP Settings

You can use your Fastmail account in a desktop or mobile email app by connecting it with IMAP or POP and sending mail through Fastmail's SMTP server. Fastmail recommends IMAP over POP, and requires SSL/TLS for every protocol. It does not support insecure access.

Use these settings to set up the incoming mail server information for your Fastmail account:

Inbound Servers:

Type	Server Address	Port	Encryption
IMAP Server (SSL/TLS)	imap.fastmail.com	993	SSL/TLS (not STARTTLS)
POP Server (SSL/TLS)	pop.fastmail.com	995	SSL/TLS (not STARTTLS)

Outbound Servers:

Type	Server Address	Port	Encryption
SMTP Server (SSL/TLS)	smtp.fastmail.com	465	SSL/TLS (not STARTTLS)
SMTP Server (STARTTLS)	smtp.fastmail.com	587	STARTTLS

Other Settings

• Username: your full Fastmail email address, including the domain. If your software has trouble with the @ symbol, Fastmail says you can try username#your.domain, username/your.domain or username=your.domain instead.
• Password: a Fastmail app password. You cannot use your regular Fastmail password for third-party apps.
• SMTP authentication: PLAIN. Use port 465 with SSL/TLS. Fastmail says to use port 587 with STARTTLS only if your client supports STARTTLS only.
• IMAP folders: leave the root folder (IMAP path prefix) blank and use / (forward slash) as the folder separator.
• Secure password authentication: do not turn on secure password authentication (SPA). Fastmail says it is not needed with SSL/TLS and will not work.
• Plan: Basic plans do not include access to IMAP or SMTP, so they cannot use third-party mail apps.

Create a Fastmail App Password

Every third-party app needs its own app password. There is no separate POP or IMAP switch to turn on. To create one:

• Step 1: Log in to Fastmail on the web and go to Settings > Privacy & Security.
• Step 2: Under Connected apps & API tokens, click Manage app passwords and access, then click New app password.
• Step 3: Choose a name for the app, then choose what it can access. Mail, Contacts & Calendars is the default and covers IMAP, POP and SMTP.
• Step 4: Click Generate password and copy it into the password field of your email app. Make sure the account works in the app before you click Done in Fastmail.

Troubleshooting

• Password error: If you use your normal Fastmail password or your two-step verification password in a third-party app, syncing will not work and you will see a password error. Create an app password instead.
• You are on a Basic plan: Basic plans cannot create app passwords or use IMAP, SMTP, CalDAV or CardDAV. You can use Fastmail in a desktop web browser or in the Fastmail mobile app instead.
• Server names: Use imap.fastmail.com, pop.fastmail.com and smtp.fastmail.com exactly as shown in the tables above.
• Ports are blocked by a firewall: Fastmail has proxy servers that work on any port number, all with SSL/TLS: imaps-proxy.fastmail.com for IMAP, pops-proxy.fastmail.com for POP and smtps-proxy.fastmail.com for SMTP. Commonly open ports include 80, 21, 25 and 443.
• Reading a folder with POP: POP pulls mail from your Inbox. To use another folder, add the folder name to your username, for example yourusername+foldername@fastmail.com. Folder names are case-sensitive and this will not work if the name has special characters.
• Wrong port or encryption: Check that IMAP uses port 993 and POP uses port 995 with SSL/TLS (not STARTTLS), and that SMTP uses 465 with SSL/TLS or 587 with STARTTLS.

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