Custom Domains with Fastmail

About domains

What is a domain?

A domain name is part of a person or business's online identity. Owning a domain lets you choose where you direct all your online activity, including for your website or your email. You might know a domain as what you type into your browser when you are trying to go to a website. Fastmail’s domain, for instance, is

Anyone can own and use a domain. A custom domain allows you to receive email at any address you like (such as, not just from Fastmail's many domains. You can host the email for your domains with Fastmail, providing at least one admin of the account has a Standard or Professional plan. Our account limits page lists how many domains and aliases each account type may have. Users on a Basic plan must use one of Fastmail's domains, however if you have multiple users on an account, a Basic user can use an address at a custom domain, providing at least one admin on the account has a Standard or Professional plan.

How do I buy a domain?

Domains can be purchased through a domain registrar. A registrar is a company that manages the purchase and ownership of internet domain names. Fastmail does not sell domains, however if you’re looking for a domain registrar, we recommend iwantmyname. There are numerous domain registrars to choose from, so it’s a matter of personal preference when deciding which one you’d like to use!

How do I use a custom domain?

Now that you’ve purchased the domain name you’d like to use, you’ll need to make some changes to your DNS records so that you can send and receive mail from your domain. These changes are to be made through the control panel supplied by your registrar.

We have an interactive guide for setting up your domain. You can add your domain and begin using the guide in the Settings → Domains screen. We will check to see if your domain is registered, and guide you through the rest of the process.

We have more information about our domain setup wizard here.

For general information about the domain setup process and detailed guides, see below.

There are three different ways you can use Fastmail with your custom domain.

Nameservers hosted with Fastmail

  • This is the easiest, most commonly used option.
  • Host your custom domain with us: we will automatically configure your domain for email support, calendar syncing, contacts syncing and other security best practices (DKIM, SPF and more).
  • You will be able to manage your domain easily within your Fastmail settings. You can update your domain records if you want a website or want to use other services being hosted elsewhere.
  • We can detect many common configuration errors and will alert you to any issues.
  • It is not a good idea to change nameservers without preparation if you already have a website on your domain.
  • Step by step instructions on adding your domain to Fastmail with NS/MX

Nameservers hosted elsewhere, but MX records pointing to Fastmail

  • For users whose domain is already hosted elsewhere (and have no ability or desire to change nameserver host), but who would like to use Fastmail for mail hosting.
  • Changes must be made on the control panel supplied by your domain registrar. We provide you with the values you'll need to add to your DNS records.
  • Fastmail can detect some MX-related set up errors, and we'll notify you if there are issues.
  • Step by step instructions on adding your domain to Fastmail with MX-only

No NS/MX at Fastmail, but mail redirected to Fastmail

  • In rare cases, Fastmail isn't hosting the nameserver or the mail exchange records, but mail is still being redirected to Fastmail.
  • Use this option if you're using a third party filtering service to process mail before it is sent to us.
  • Fastmail's own spam filtering will be much less effective if you use this option.
  • We provide all the values you'll need to configure on your current MX server to ensure correct mail delivery. Fastmail is unable to detect misconfigurations in this case, as all the domain management is held elsewhere.
  • Step by step instructions on adding your domain to Fastmail with no NS/MX

Please note that only account administrators can manage custom domains on an account. If you’re not an administrator of your account but would like to use a custom domain, or are having issues with your domain, please be sure to contact your administrator.

Mirrored domains

With email, it's easy to have multiple domains that "mirror" each other. So you might have and, and you want any email address at to work at as well. To set this up:

  1. Pick a "primary" domain (say, and create all your domain aliases and accounts in that domain.
  2. Create a single alias in your alternate domain with the special * (star) value (e.g. * and set the target of that alias to * Then any valid email address at, will also work at Note that this only works for email addresses; for websites, you have to explicitly create the website for each domain, or set up a redirect to the primary domain.
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