August 22, 2022 5:50 PM, "Viktor Dukhovni" <postfix-us...@dukhovni.org> wrote:
> Best to ignore bad advice. You may need a better antispam filter. Ad > hoc rules for past (and plausibly never again) abuse are not likely to > be effective. That said, no antispam filter is 100% effective. Some > spam *will* get through no matter what you do. I fully subscribe to this. I'm just quite stunned that those messages passed through despite so many red flags. I've looked for a spamassassin plugin that would deal with that but could not find one. I would say that a message created by MAILER DAEMON should not be sent to BCC only, any email address in headers (Reply-To here) should have a valid MX record, a non-empty "From" (string "Recipients" here) should always be a valid email address, etc. As I understand it, some of these "headers" are not part of the envelop so it's probably impossible to enforce something at SMTP stage. I'll dig in spamassassin arcanes for a possible tunable… thanks patpro
