We have cleaned up the spam on server NC027 and managed to funnel most of the delayed email through our relay server. Although the primary mail server’s IP address is not in a couple of the major blacklists, we are still in some niche ones with major ISPs and mail providers. We have been working to have the IP address de-listed where that is possible, but manual processes like these can take a couple of days.
In the meantime, at the moment most email is flowing normally, but email to most domains will still be delayed for the next few hours.