With your own domain name and access to its DNS records, you can fully align your email experience with your brand, and improve your deliverability.

This article will help you to prepare your domains and DNS for use with Campaign Monitor. You will then be able to use them for:

• Custom domains — Used for the URL you log into Campaign Monitor with, campaign tracking links, subscription confirmation pages, links in verification emails, and "view in browser" links.
• Email authentication — Including DKIM, SPF, and DMARC, which work together to improve your deliverability and protect your brand.

Before you start

Using your own domain with Campaign Monitor is a technical process. It requires:

• Working with systems outside of Campaign Monitor that you have access to, but we don't.
• Knowledge of how domains work.
• DNS knowledge.
• An understanding of public/private keys.

If terms like TXT records, CNAME records, public/private keys and TTL settings aren't familiar to you, ask someone in your IT department for help, or find a technical friend.

Check your TTL

The Time To Live (TTL) of a domain's DNS records determines how often DNS servers around the world check in to see if there are changes to those records. This isn't a simultaneous check, but is staggered, based on when each individual DNS server checked in last. Because internet users around the world are connected to different DNS servers, this means when you make a DNS change, it's possible that for a period of time two different people in different parts of the world will see different values for the same record in your DNS — one the old record, one new.

Each DNS host sets a different TTL for its DNS records, and different record types can have different TTL lengths. Some TTLs can be as high as 48 hours, meaning it could be up to two days before parts of the internet see any changes you've made.

Because of this, it's a good idea to reduce your TTL before changing DNS records. This means you can more quickly test DNS changes yourself (as the DNS server you're connected to will see those changes sooner), correct any mistakes you've made faster, and that people around the world will see your updates quicker.

Many DNS hosts allow you to lower the TTL on a record yourself to a custom value, or temporarily lower it, for example, to 5 minutes over the next 72 hours. Other DNS hosts you will need to contact directly to have the TTL lowered.

It's a good idea to plan a TTL change in advance. This is because when you change a TTL value, the original period still needs to run out before all DNS servers see that they should check in more regularly. For example, if your original TTL on a record is 48 hours, and you reduce it to 5 minutes, you will still need to wait for the initial 48 hours before you can guarantee all DNS servers around the world will be checking in at the increased rate. In this scenario, you'd lower your TTL, wait 48 hours, then begin to make your changes.

After you've successfully made the changes, if it's not automated, make sure to return your TTL to its original value.

Use a good DNS host

Each DNS host has a different setup, and some don't allow you to make certain changes, or use certain characters. Your DNS host will need to support the following to use your own domain with Campaign Monitor successfully:

• 255 character TXT record lengths — Our standard DKIM key is 1024-bit, which is 225 characters long. Some DNS hosts allow significantly less than the full 255 character limit for TXT records, and this can cause issues.
• Underscores and semicolons — DKIM records include an underscore (_) and semicolons (;), and this can't be changed. In some cases, substituting ; for \; can bypass the lack of support for semicolons in a DNS host.
• Fourth level domains — For example, cm._domainkey.example.com. If you're having difficulty adding your DKIM record to your sending domain, try adding a subdomain called _domainkey, then add a subdomain to that called cm. Next, add the DKIM details to a TXT record on the cm subdomain.

If your DNS host doesn't support the above in their web interface, it may still be possible to make the changes you need by reaching out to the DNS host's support. If not, you will need to find a host that gives more flexibility.

Set up subdomains

Unless you've set up a domain purely for email, there's a high chance your second level domain (the example in example.com) is already being used to serve your website. In this case, we recommend reserving one or more subdomains for use with your email marketing. Depending on your business size, you may only need one dedicated subdomain, or you may want several if you're managing communications from multiple departments.

For example, in an account with multiple clients, you might set something up that looks similar to the following:

• e.example.com — Used by the example client to log into their own account. This will also be used for almost all links in the emails they send, and for subscription confirmation pages.
• hello.example.com — Used by the example client to send onboarding emails from.
• orders.example.com — Used by the example client to send invoices from.
• news.example.com — Used by the example client to send feature update newsletters from.

Next steps

Now that you've got the essentials in place, you can set up the following:

• Custom domains — Used for the URL you log into Campaign Monitor with, campaign tracking links, subscription confirmation pages, links in verification emails, and "view in browser" links.
• Email authentication — Including DKIM, SPF, and DMARC, which work together to improve your deliverability and protect your brand.