In our continued efforts to protect our mail servers from both spam, virus and harvesting attacks we have implemented blocking of dynamic IP ranges.

This means that if the IP connecting to our mail servers returns as from a dynamic IP range we will drop the connection and not accept the mail.

Dynamic IP ranges are the IPs assigned by ISPs to their users when they connect to the internet. They are called Dynamic because they change everytime the user connects and are not specifically assigned to the user. Many spam and virus attacks come from compromised systems or systems connected to the internet through a dial-up or broadband account. Blocking these types of IPs means that they can not directly connect to our mail server. It does not mean that mail sent from a dynamic IP will always be blocked. It will only be blocked if it is sent to us directly rather than through an ISP mail server.

If you run your own mailserver on your broadband connection then you should check that your ISP has assigned you a static IP address and that the IP address is not labelled as dynamic.

If a direct connection is made from a dynamic IP rage then the following error will be given by our mail servers

554 5.7.1 We do not accept mail from Dynamic IP Ranges

We will then also tarpit the IP for 60 minutes.