Setting up your domain: MX only

There are just three simple steps:

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

Verifying

Optional set up

We have handy guides for setting up your domain's MX records with a few common domain registrars:


1. Add your domain

Go to the Settings → Domains screen. Then, add your domain(s) (e.g. mydomain.com).

Clicking the Add Domain button brings up the new domain screen. Type your domain into the text box.

add domain screen

2. Domain registration set up

Note: Updating your DNS is a big change: we recommend updating it at a time you don't expect much mail.

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 subdomains to come to us as well, you need to set the MX records for *.mydomain.com to the above values as well.

Some DNS providers require that you put a . on the end of the MX server names (e.g. in1-smtp.messagingengine.com. rather than in1-smtp.messagingengine.com). 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 make sure messages are sent from your domain without issue. These are the values you need (make sure you replace {mydomain.com} with your actual domain!):

TypeSelectorValue
TXT (leave blank) v=spf1 include:spf.messagingengine.com ?all
CNAME fm1._domainkey fm1.{mydomain.com}.dkim.fmhosted.com
CNAME fm2._domainkey fm2.{mydomain.com}.dkim.fmhosted.com
CNAME fm3._domainkey fm3.{mydomain.com}.dkim.fmhosted.com

If you use Cloudflare, you should see an orange cloud icon when editing your CNAME entries. Cloudfare supports CNAME flattening, however we do not. Click on these orange clouds to direct traffic away from Cloudfare and turn off CNAME flattening.

Once we detect that 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 your Settings → Users & Aliases screen. You can add up to 600 aliases. You may also choose to add a catchall alias so any mail addressed to any address at your domain comes to you.

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

If you'd like to set up your account to send using one of your custom domain addresses by default:

You can also choose an Identity to use as the default for sending mail within a given folder.


Verifying

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. Once your domain is set up correctly and active on Fastmail, messages sent to the addresses you added on the aliases screen should now arrive in your Inbox.

How do I know it's right?

Your Settings → Domains screen shows a green tick when it has detected that your DNS entries are complete and correct. Any lingering issues are marked with a red exclamation point and a recommendation on how to resolve this issue.

greentick

There are many online tools to check the set up (such as MX Toolbox).


Optional domain set up

System email addresses

The email standard requires that the email address postmaster@yourdomain.com 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 abuse@yourdomain.com. By default, if you don't set up your own alias for abuse@yourdomain.com, we'll automatically direct all email sent to abuse@yourdomain.com to our 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: