As a server administrator and domain owner, there are many things that you can do to help thwart spam from arriving in your users' inboxes. This page will outline some of the basics to get you headed on the right track towards filtering out the spam and keeping your server off the Real-time Block Lists. Proper DNS entries The first thing you need to double check is to make sure that your server's mail hostname(mx record in DNS) resolves to the IP address your mail server software runs on. This is necessary in order for mail to pass properly. The second thing to double check is to make sure the reverse DNS for the same IP resolves back to the same mail hostname. An example of this might be: root@server:~$ host mail.sagonet.com mail.sagonet.com has address 66.118.128.47 root@server:~$ host 66.118.128.47 47.128.118.66.in-addr.arpa domain name pointer mail.sagonet.com. SPF Record SPF records are becoming more integral as time passes. Many providers are already starting to choose to filter domains that do not publish SPF records. What is an SPF record you ask? It stands for Sender Policy Framework. And here is how it works: This technology requires two sides in order to be implemented: (1) The domain owner publishes this information in an TXT(SPF) record in the domain's DNS zone.
(2) The receiving mail server can check whether each message complies with the domain's stated policy, via DNS.
The best practice for implementing an SPF record requires you, the domain owner, to publish an SPF record stating the IP address of your mail server. This allows mail servers such as ours to ensure that no other mail server other than your own is sending us email for your domain. Any email that arrives to our mail server that is NOT from your mail server(as stated by your SPF record), will be rejected and will not reach our customers. Currently on the Internet, SPF records are still quite a rare thing. With your help, we can change that and start winning back our Inboxes in the war against spammers. Here are some invaluable resources to learn more about SPF, and how to implement it:
Any mail software that you run has the capability of utilizing a virus scanner to ensure that messages that arrive at your mail server are clean of viruses. clamAV is one such program. It not only scans for viruses, but also scans for malformed email content. It is highly recommended to make use of such a virus scanner on your mail server. SpamAssassin SpamAssassin is by-far your largest tool in the fight against spam. There are many resources online that delve into the specifics of how to set up SpamAssassin properly. Below are some of the sites that we recommend you visit:
As a service to you, Sago Neworks scans all emails coming in to both our corporate and customer mail servers and generates a list of the largest spammer IP addresses. We then insert these IP addresses into a Real-time Block List that can be utilized by anyone on the Internet. We strongly recommend utilizing this service with your mail server to help thwart some of the larger attacks that you may see as a Sago Networks customer. There are links at the top of this page which explain how to implement the RBL. |