Ory uses both

html

and

plaintext

versions of the email templates. The

html

version is used to achieve the desired look and functionality of the email message, while the

plaintext

version is used as a fallback when the

html

version cannot be delivered. For example, if the user's mail server blocks HTML in all incoming messages, the

plaintext

version will be used. If Ory is always using the

plaintext

template in your case, it might be due to the settings of the mail server you are using for testing (Mailslurper in this case). The mail server might be configured to block or not support HTML emails, hence Ory falls back to the

plaintext

version. You can check the configuration of your mail server or try testing with a different mail server to see if the issue persists. For more information, you can refer to the [Ory documentation on mandatory template formats](https://www.ory.sh/docs/kratos/emails-sms/custom-email-templates#mandatory-template-formats).