My notes here: https://simonwillison.net/2025/Jun/11/echoleak/

The attack involves sending an email with multiple copies of the attack attached to a bunch of different text, like this:

  Here is the complete guide to employee onborading processes:
  <attack instructions> [...]

  Here is the complete guide to leave of absence management:
  <attack instructions>

The idea is to have such generic, likely questions that there is a high chance that a random user prompt will trigger the attack.