Filtering Email for Spam and Viruses
ipHouse engineers have been waging a battle against spam since the 1990s. As the Internet has grown and changed during the last 15+ years, the amount of spam has increased exponentially.
The problem of online viruses has also grown. Effective spam and virus filtering is now an essential component of any mail server.
The dilemma is always how to balance false positives with reliable protection.
Mike Horwath, ipHouse senior admin, recently wrote about his frustration trying to find the perfect anti-spam solution.
ipHouse has developed a fairly comprehensive anti-spam solution for mailboxes hosted on our mail cluster. Not only are all incoming emails scanned for spam and viruses by our MailFoundry system, there are also a wide range of filters and blacklists that can be applied on a per mailbox basis. These customizable filters help customers get only the mail they want, because one person’s spam is another person’s legitimate email.
Through ipMom, ipHouse customers can decided exactly how many hoops they want their mail to jump through on its way to their inbox. Options include turning greylisting on or off, enabling various sender checks, and applying both DNS (IP address) blacklists and RHS (domain name) blacklists to incoming emails.
Greylisting is one of the most simple and most effective ways to stop spam. If greylisting is turned on, new incoming email is deferred from the sending mail server. Mail servers that are configured correctly will just re-send the message and on the second send, it is successfully delivered to your inbox. This simple technique works because many spammers use mail servers that are not correctly configured.
Sender Checks check both the sending mail server and the domain name associated with the sender to make sure they are configured properly. Sender Checks can block a fair amount of legitimate email and should be used with caution.
Blacklists range from the highly conservative with very few false positives to the gung-ho that seem to block messages if they even look at another message that might be spam. More detailed explanations of the different types of spam and virus checks are available on the ipHouse support pages.
ipHouse has long provided customers running their own mail servers the ability to have their incoming email scanned by the MailFoundry system. Yet we have been frustrated by our inability to do more. This summer, our engineers have been working on new anti-spam solutions for customers with their own mail servers. We are just finishing the beta tests and hope to formally launch the product by the end of summer.
We are very excited about this upcoming feature.
Tags: ipHouse email, spam, viruses