Hard evidence, it depends what you mean by this. it is difficult to check but certainly if we test our emails, for example on mail genius it gets flagged up. Given that we don’t spam, use a mail relay, use dmarc etc.. as a rule the only thing we have found to explain it is the domain is in their 2 & 3 list.
e.g. Test Failed – mail genius – Your domain is listed on significant blacklists. – Severity of the problem: High