For “normal members” I disabled “Request notification on replies” and “Request notification on new topics”.
I’m pretty sure there’s a notification option for when you receive PMs, but I don’t see a way to disable it. If we have to, I guess we could edit the php code.
Source: Published by Martti Malmi on GitHub in February 2024 as part of his testimony in the COPA v. Wright trial. The full correspondence archive is available at mmalmi.github.io/satoshi/.