Configuring the IMAP path prefix

When your mail client talks to our server, it needs to know who you are (your name and password), how to talk to us (the server name and port) and where to look for your mail (this is the IMAP path prefix).

Usually your client gets all this information right and your email Just Works. Sometimes, it gets it wrong and then you find that either:

To fix this, check the advanced account settings in your mail client for your Fastmail account. We support connecting to us in one of two ways:

For imap.fastmail.com:

For mail.messagingengine.com:

Whatever your mail client currently has set, try the alternative and see if that works.

Apple Mail

Apple does try to be helpful and auto-detect the settings for you, including overriding any manual settings you have set. Which is not as helpful as they might think.

If this is a problem, unset the "Automatically detect and maintain server settings" option on your account in the Mail client.