On the Free Plan, you can typically authenticate one sender email domain. With paid plans, the limit often increases, depending on the provider and plan tier. For specific details on how many domains are allowed per plan, I recommend checking your provider's pricing or account settings. Let me know if you’d like further assistance!

Welcome to the Klaviyo Community, ​@cmhaywood!

Klaviyo accounts are designed to support one primary sender email domain per account. This means that if you wish to authenticate multiple sender domains, you'll need to set up separate Klaviyo accounts for each domain. This approach ensures optimal deliverability and maintains a strong sender reputation for each domain.
 

While you can send emails from multiple addresses within the same domain (e.g., support@yourbrand.com and marketing@yourbrand.com), authenticating additional domains within a single Klaviyo account isn't supported.

For more detailed information, you can refer to Klaviyo's official documentation on setting up a branded sending domain: Klaviyo Help
 

I hope this help! Feel free to reach out if you have any further questions.