Can't send an automatic email when validation rule is triggered

Question

When I get an email from specific email address with specific subject, I want to:

1. Block this email from creating a case
2. send an automatic email to this email address that their case wasn't created.

I did the first step with a validation rule on the email message object, but I don't know how to send the automatic email when the validation rule is triggered.

Answer 1

Stopping a record from being created through a validation rule also prevents all side effects, such as sending an email. Instead, you would want to send an email first, then delete the case after the initial transaction completes (e.g. with an asynchronous flow path, future method, etc).