Fysh.Org Email Statistics - Rejections in the last year

• spamhaus.org - Rejects due to listing on a Realtime BlackList (RBL) at Spamhaus. As of 2016-04-29 we use the zen.spamhaus.org DNSBL.
• unknown-user - Email was attempted to a user we don't have. Could have been a typo by the sender, but could also easily be a spam attempt with out of date or erroneous data.
• temp-greylisted - One of the temporary rejections that greylisting can cause. Such email may have been delivered later.
• local-blacklist - Our local list of hostname patterns that we think means the host shouldn't be trying to send email directly to us. These will almost invariably be dialup, cable and DSL connections used by home machines. They can easily use their ISP's email server to relay via to get email to us. We reject these hosts because such direct attempts have a high probability of being from spam-sending trojans.
• sender-verify-failed - When someone tries to send email to us we check to see if email could actually get back to the purported sender. We reject the email if not.
• unrecognised-lines - These are usually mostly caused by users having control of the aliases for their domain that is delivered on fysh.org, and they've set up aliases that use exim's ':fail:' target. Thus the rejection reason is defined by them and the scripts that generate these graphs don't recognise it. However, do note that 'relay not permitted' will also fall into this category. It's usually rare, but there have been instances of botnets attempting mass-relay at times.
• sender-verify-incomplete - Similar to sender-verify-failed, but the check didn't entirely fail, instead something stopped it from working to completion. This is a tempoary rejection.
• rcpt-callout-said-no - We relay email for some domains through fysh.org. Because we don't control the final destination we don't automatically know if an email address in the domain is valid. Rather than blindly relay, which raises the possibility of the final destination rejecting spam back to us, we attempt to check if the recipient is valid for forwarding on ('recipient callout verification') before we accept the email. This count is for such to-be-relayed emails that failed this check.
• temp-greylisted-rcpt-callout-incomplete - Another greylist temporary rejection. This time it's because we couldn't complete a recipient callout verification