Can spam controls permanently block delivery?
We sometimes see remote mail systems that do not obey the greylisting request to return after 14 minutes. Either they retry more frequently (and each time are told to come back later), or they retry delivery from a different mail host. In either case, mail is effectively blocked permanently. There is nothing that we can do about this, since the fault lies in a remote system that is not under our control. If this happens to you, it is your responsibility to contact the remote mail administrators and get them to fix their problem. They are then welcome to contact our local systems staff to discuss the technical issues in more detail, if necessary. It is rare for mail-delivery problems to be at our end. Our mail server runs on a highly-reliable system with redundant hardware components and backup power generation, is closely monitored by a mail-software wizard, successfully delivers and receives several thousand messages daily, and has done so for three decades. If mail is blocked by the
