Configuring your domain with MX only

There's just three simple steps:

  1. Add your domain
  2. Domain registration configuration.
  3. Add email addresses at your domain


Optional configuration

1. Add your domain

  1. Go to the Settings → Domains screen. .
  2. Add your domain(s) (e.g. Clicking the "Add Domain" button brings up the new domain screen. Type your domain into the text box.

2. Domain registration configuration

Note: Updating your DNS is a high visibility change: we recommend updating it during a time when your site has low traffic

Set your MX records to:

If your DNS provider asks for a host name, this can be entered as @.

These should be the only two MX records listed for your domain. If you want email for sub-domains to come to us as well, you need to set the MX records for * to the above values as well.

Some DNS providers require that you put a . on the end of the MX server names (e.g. rather than Try the version without a . first, and if the DNS provider adds anything, try adding the ..

In addition to MX records, we strongly recommend you add SPF and DKIM entries to help ensure messages are sent from your domain without issue. These are the values you need (make sure you replace {} with your actual domain!):

TXT (leave blank) v=spf1 ?all
CNAME fm1._domainkey fm1.{}
CNAME fm2._domainkey fm2.{}
CNAME fm3._domainkey fm3.{}

Cloudflare users should click the orange cloud icon when editing CNAME entries to route traffic away from Cloudflare.

Once Fastmail has detected your MX records are set up correctly, go to Settings → Domains, click Edit on your domain and we'll show you if everything is set up correctly.

See our DNS page for more information.

3. Add email addresses at your domain

To set up email addresses for your custom domain, add aliases at Settings → Users & Aliases. You can add up to 600 aliases. You may also choose to add a catchall alias so any mail addressed to your domain comes to you, no matter what address is used.

Creating an alias also creates a matching account identity. This lets you send mail from your account using the email address matching that alias. You can customise other settings too, such as your signature.

If you'd like to configure your account to primarily send using one of your custom domain addresses:

  1. Navigate to the Settings → Sending identities screen.
  2. Select your alias in the "Compose new messages from <address> by default".

You can also select an identity to use as the default account to use for mail being sent from within a given folder.


How long until it's working?

Depending on the TTL values for your previous DNS settings (if any), it may take up to a day for the changes to propagate across the internet. Normally it's a lot faster: just a matter of minutes. Messages sent to the addresses you added on the aliases screen should now arrive in your Inbox.

How do I know it's right?

The Fastmail interface shows a green tick when it has detected that your configuration is complete and correct. Any outstanding items are marked with a red exclamation mark and a recommendation provided on how to address this issue.

There are many online tools to check the configuration (Such as MX Toolbox).

Optional domain configuration

System email addresses

The email standard requires that the email address be a valid email address. Because of this, even if you don't set up an alias for that address, we will deliver any email sent to that address to the owner of the domain.

It's also best practice to support By default, if you don't set up your own alias for, we'll automatically direct all email sent to to our automated abuse handling system.

Subdomain addressing and mail routing

On the Settings → Domains screen, you can control subdomain addressing and mail routing.

The Mail: Subdomain section lets you control how Fastmail handles subdomain addressing for your domain. There are three options:

The Mail: Routing section lets you choose how mail to this domain is handled. Use: