IMAP, POP, and SMTP are standards that allow you to connect your Fastmail account to a third-party email client of your choice. This page details the differences between the three options to help you choose the right one for your circumstances.

All connections over IMAP, POP, and SMTP need their own app password to access your information. If you use your normal password or your Fastmail two step verification password on an external client, syncing won't work and you will see a password error.


In most cases, IMAP is the best way to connect your email client to read your emails. IMAP is a newer standard than POP, and is the most widely used option.

When you connect your account with IMAP, you can download messages from any folder on your Fastmail account. This means IMAP is a good option if you use rules to organize your mail.

IMAP lets you manage your account wherever you need to do so. Because it offers two-way sync between the client and the server, any changes that you make on the client of your choice will be reflected in the Fastmail web interface. Similarly, changes you make on the Fastmail web interface, like moving your message to a different folder, will show up on your mail client as well.


POP is an older standard that has mostly been replaced by IMAP.

By default, POP will only download mail from the Inbox, and not from any other folder. This means that if you use folders for organizing your mail, you will need to do this manually on your device instead of using rules to do this automatically.

POP can only download messages and does not sync from your client to the server, meaning that any changes made on the email client, like moving a message to a different folder, will not be reflected on the web interface or anywhere else you access your email.

POP is an option for users who would like to keep a local offline backup of their Inbox.


SMTP is used by email clients for message submission to let you send emails through the Fastmail servers to your recipients. SMTP will need to be set up alongside either IMAP or POP so that you can send messages on your client as well as receive them.

The Fastmail IMAP, POP, and SMTP servers

The Fastmail server names and ports are:

IMAP Port 993
POP Port 995
SMTP Port 465 (SSL) or 587 (STARTTLS)

For more detailed information on Fastmail servers, please see our Server names and ports help page.

Firewall access

If you are behind a firewall, some service ports may be blocked. Fastmail has a special proxy system whereby you can access IMAP, POP, and SMTP through any port number. All these servers use SSL/TLS. The server names are:


If you use these server names, you can use any port to access these services. Commonly open ports include 80, 21, 25, and 443.

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