Recently we have been the target of large scale DDOS attacks against our SMTP servers. This has caused some email delivery delays. Considering how effective our new susranges system has been at rejecting spam, it's very likely that we've upset a spammer with a large budget. Presently, these are mitigated. However, for the last 3 hours we have accumulated just over 18,000 emails that were delayed and are now being delivered.