Understanding what a branded sending subdomain is

You will learn

When setting up a branded sending domain (also known as a dedicated sending domain), you choose an associated subdomain or prefix. This article explains how to choose a subdomain appropriate for your business, including when you set up multiple branded sending domains across different send types.

Understanding sending domain prefixes

A sending domain is the domain from which your emails are sent and appears in your email header. Each domain begins with a subdomain. For example, if your sending domain is send.helloworld.com, the subdomain is send.

You can choose any word as your subdomain, provided it is not already in use within your DNS (domain name system). However, choose a word that aligns with your brand and sending purpose. "Send" is the most common prefix for dedicated sending domains and is Klaviyo's recommended choice for marketing traffic, as it typically remains unused by other services within a DNS.

The prefix must be 63 characters or fewer and cannot contain spaces or accented characters.

Sending domain prefix best practices

When setting up your branded sending domain in Klaviyo, enter only the prefix (for example, send) under Sending domain. Klaviyo combines it with your Root domain to form the full sending domain, such as send.helloworld.com.

Keep these best practices in mind when choosing a subdomain:

• Choose a subdomain that is not used by another service
  Check your DNS provider's records before choosing a subdomain. Using a subdomain that already points to a website, inbox, or another email service can conflict with the DNS records Klaviyo needs.
• You can share a sending domain across Klaviyo accounts
  In Klaviyo, you can use the same sending domain for multiple accounts. For example, if you manage a US and UK account for a given brand, you can use the same sending domain for both. Choose the same routing type and email type in each account. The CNAME or NS records should be the same, but each account will have a different TXT verification value. Add each account's TXT verification value to your DNS records.
• Your subdomain should suggest email sending
  Though you can choose any word for your subdomain, choose one that implies email sending. Other users of your DNS can then easily identify your subdomain, which reduces the chances of another user deleting or editing it by mistake. When you review your DNS records in the future, you will see this subdomain and easily know that it is for dedicated sending.
  For example, subdomains such as send.helloworld.com, emails.helloworld.com, or newsletter.helloworld.com can all work for marketing.

Choosing subdomains for multiple send types

If your account has more than one branded sending domain (for example, separate domains for marketing, transactional, and service traffic), each domain needs a unique subdomain under the same root domain. You cannot add the same full sending domain twice in one account.

To select Service during setup, inbound email must be enabled for your account.

A common pattern is to use the "send" subdomain for marketing and choose different subdomains for transactional and service traffic. For example:

• Marketing: send.helloworld.com
• Transactional: updates.helloworld.com or notifications.helloworld.com
• Service: support.helloworld.com or help.helloworld.com

You can choose any subdomains you like, as long as they're not already in use elsewhere on your DNS. Pick names that suggest the purpose of each domain so they're easy to identify later.

Additional resources