To encode the secret (such as the password) in the SMTP connection string for Ory Kratos when it contains special characters like @, you must URL-encode the username and password. Special characters (including @, /, %, $, etc.) must be percent-encoded to ensure the connection string is valid. For example, if your password is pass@word, you should encode it as pass%40word (since %40 is the URL encoding for @). You can use tools like JavaScript’s encodeURIComponent or an online encoder:

javascript console.log(encodeURIComponent("pass@word")) // Outputs: pass%40word

So your SMTP connection string would look like:

<smtp://username:pass%40word@email-smtp.eu-west-3.amazonaws.com:587>

This approach applies to both the username and password fields in the connection URI. Always ensure your credentials are properly encoded to avoid configuration errors and potential security issues. For more details, see the official troubleshooting guide on invalid SMTP courier URL format [Invalid SMTP courier URL format (OTA-112022-01)](https://www.ory.sh/docs/troubleshooting/smtp-courier-OTA-112022-01).