Template emails: rendering failures

If you have an error in one of your email templates, or any code that uses them, you may end up with a "Rendering Failure" - SES will return a status code 200 as if it had sent the email, but will not actually have sent the email.

The only way to know these occur is to ensure you have your SES configuration set properly configured to send error events, including rendering failures, to an SNS topic and make sure the topic is subscribed to (e.g. by an SQS queue).

For instance, say you have an email template with two variables in it:

{{username}}
{{coolstuff}}

If you have some code that doesn't assign any value to {{username}} and attempts to send a templated email, SES will seem to send the email correctly, but will in fact fail to send it. This silent error can be awkward to detect, so keep an eye on your email error queue and be careful about sending templated emails correctly.