I usually check the "Received" header and report to the email service provider. Once in a while I receive a response saying the case is properly handled.
These providers are the only ones that care about their reputation and thus may take some action. Investors? Nope.
the problem is that the emails arent typically sent from the main domain.
in this example, the email came from buildrunanywhere.org, which is just a parked domain. the real domain is runanywhere.ai, which they arent using for spam.
so, once buildrunanywhere.org has their reputation burned from reports, they will simply register buildrunanywheres.org and start spamming again.