Im getting annoying and unwanted emails (gambling related, not spam though. Someone is using an address) and trying unsuccessfully to block the emails from being accepted by Postfix/rspamd. I want to block <Everything>@unwanted.domain ideally from being accepted at all, failing that by spamfilter. I tried adding @unwanted.domain to the blacklist spamfilter via roundcube but it doesnt seem to work. Next i tried the Postfix blacklist in ISPConfig (3.2 latest) and it doesn't seem to work either. Neither as a specific full email address or the domain. To clarify, this isn't spam as such - the mails appear genuine and from an actual entity but they're unwanted and it seems someone is simply using the email addresses to register on sites. Anyone tell me where im going wrong or where the proper place to add this block would be? (and what format it would be?)
In the panel: Email > Content filter > Add new content filter Regex: Code: /^From: .*@example.com/ Action: Reject