When rejecting emails that are classified as spam by whatever means, there's always the chance of false positives. On the other hand, when accepting emails that may be spam and dumping them into a spam folder the owner of the mailbox might not check that folder and miss an important email while the sender assumes it has been delivered.
I think the perfect solution for this would be to reject the email as far as the sender is concerned but still deliver it to a spam folder.
So my questions are:
- Is it possible/allowed for an SMTP server (as far as the SMTP protocol and related RFCs are concerned) to reject an email after receiving everything (i.e. all header and the full message body) without errors?
- Is it possible to achieve this behavior with Postfix, ideally without having to modify its code.