Within the last few hours, the IP address of server NC020 has been added to the Spamhaus Policy Block List (PBL). This is well-known, major and useful anti-spam block list operated by a reputable anti-spam organisation, and we ourselves use this block list to protect our clients from spam. However, this affects our clients in four ways:
- Clients who use the relay server (NC020) may find that some of their outbound email will be delayed or rejected by destination servers. This is our primary concern at the moment, and we are working with the data centre (the company that actually owns the IP address) and, through them, Spamhaus to have the IP address removed from the PBL. Unfortunately, because this situation has just arisen with no notice, things are in a state of flux at the moment so we don’t have any idea when this will happen.
- Because there is a lot of email traffic from server NC020 (the relay server) to NC018 (our primary server), and because server NC018 uses the PBL to block spam, some clients sending email through the relay server to domains hosted by us would have found that their email was not delivered in the last few hours. We have since stopped using the PBL to block spam on server NC018, and so that email is flowing again. Any email that was delayed has now been delivered, and was not deleted or bounced.
- Because we have stopped using the PBL to block spam on server NC018, that means that clients with email hosted on that server (most of you) have just a little bit less spam protection than before. However, we use a number of effective block lists, and hopefully the temporary removal of just one of them won’t have a major impact. Once this situation is resolved, we will reinstate use of the PBL to protect you from spam.
- Finally, if you are operating your own mail server and are using the PBL, we suggest that you disable use of the PBL for now so that you can receive email that passes through server NC020. This would apply to you if you are using our back-up mail server (MX) service.
We will, of course, post further updates here as we learn more and as the situation progresses. We appreciate your patience.
