So your Exchange Transport rule (ETR) or Data Loss Prevention (DLP) rule is not working as expected...
... and troubleshooting this issue can get extraordinarily complex, especially if it´s hard to reinitiate the sent email to check adjustments. For many years this has been a recurring question and feedback we got from you.
Let´s look into today's situation, taking this example. With two configured ETRs, as usual, rules have been configured and shortly after that, feedback comes back that it´s not working. In the first steps, the admin revisits the rule and does some sanity checks for typos or the correct ordering. But that seems to be fine.
Before we dig deeper into that one thing to be aware of is the pipeline order of processing ETR and DLP rules. ETR is processed before DLP comes into play, so anything made in ETR would be available for DLP. But not the way around.