They mention writing a test to verify the behavior on the core mempool, which worked as expected. The author also provides a link to the commit on GitHub for reference.

They inform the recipients that they are halting their involvement with the development of the lightning network and its implementations, including coordinating the handling of security issues at the protocol level. They have already informed some senior lightning developers about this decision. The author closes an old issue related to this purpose on the bolt repository and shares the link.

The author expresses concern about a new class of replacement cycling attacks that put the lightning network in a perilous position. They believe that a sustainable fix can only happen at the base-layer, such as adding a memory-intensive history of all-seen transactions or implementing a consensus upgrade. While deployed mitigations are effective against simple attacks, they believe advanced attackers are not deterred. They emphasize that such changes require transparency and buy-in from the community as they impact the processing requirements and security architecture of the decentralized bitcoin ecosystem.

The author acknowledges the challenge of fully explaining the need for these changes and suggests that practical and critical attacks on a significant portion of the BTC ecosystem may need to be presented to justify them. They acknowledge the difficulty in balancing the need for transparency with the risk of exposing vulnerabilities. They plan to remain silent on these issues on public mailing lists until the week of October 30th, as enough material has already been published and other experts are available. Afterward, they intend to shift their focus back to bitcoin core development.

Overall, the email highlights the author's concerns about the lightning network's vulnerability to certain attacks and the need for significant changes at the base-layer. They express their intention to step away from lightning network development temporarily and focus on bitcoin core.