Our person in charge has consulted with their previous person in charge, and their response is this.
"problem began long before February 18th. The problem was that in 2022 they added our prefix
87.251.79.0/24 to the black list, and said that if there were no complaints for 30-60 days, the record would be deleted. we agreed, almost a year has passed, the record has remained. They tried several times to put pressure on our providers, but we always record any termination of the contract with large fines, not a single provider has done this, we pay a lot of money for the Internet, and no one wants to take risks, now spamhouse pressure on"
Actually, I didn’t know what a spamhouse was before this month, until we announced the IP in vultr
They claim they've been working on the issue, but I've found that they don't respond to emails very well (I can only judge from this). Usually though, I tell them to take down the content, and then the content gets a different provider.
Also, it's not clear to me whether we need to reply to emails sent from the spamhouse system. They claim that they took care of the content, but I personally think it's because they didn't respond to the email that spamhouse thinks they're not doing it