Rich Kulawiec wrote:
notification is essential in order to provide a heads-up about problems (and that once problems are noticed, cooperation is essential in order to fix them). But mail should never be discarded without notice
In practice we've found that (notification) is the core issue. Reject v discard is a non-issue by comparison. The format of those notifications does not have to be a spam folder, as many seem to assume. A summary report serves the purpose far better than tagging and delivery with far less overhead. Quoting <http://www.postconf.com/docs/spamrep/> : The only reliable way to avoid false-positives is by monitoring the email server or gateway logs and allowing end-users to receive a daily report of email sent to their account that was identified as spam and filtered. This is more or less identical to the issue ISP's like Comcast face when implementing QOS or other filtering, when they fail to notify end-users. Backscatter / NDNs are another issue. In practice they are no longer feasible without assurance that the sender is both valid and legitimate. Bounces without these validations are usually spam and will get your server blacklisted. Roger Marquis