Protect your Email Reputation with New Dynamic Block Rules

Protecting your email reputation is getting harder and harder, yet it is critical to successful delivery of marketing or transactional email. A large part of protecting your reputation includes honoring the requests of a seemingly infinite number of ISPs. So what is an emailer to do?

The new Dynamic Block Rules in Hurricane MTA Server provide an easy and automatic solution to protecting your reputation by automatically, temporarily suppressing delivery at the request of an ISP.

Dynamic Block Rules are a new part of Hurricane MTA Server’s Delivery Rule system. Hurricane MTA Server’s Delivery Rules enable traffic shaping to specific ISPs. The new Dynamic Block Rules are a subset of a Delivery Rule. The Dynamic Block Rule system scans ISP responses for known codes and text which indicate that the ISP wants you to pause sending them email. The Dynamic Block System then automatically pauses delivery to that ISP for the time period set up in the block rule.

Multiple Dynamic Block Rules may be specified for each Delivery Rule and they are evaluated in the order of their priority, top-down, until a match is made, in which event that rule is activated. Only one rule can ever be active at one time. Each time a Dynamic Block Rule is activated, a Delivery Alert will be posted to the Hurricane MTA Server alert system. There is also a Dynamic Block Rule option to “Only Alert” without pausing delivery.

Each rule consists of the following pieces of information:

Setting Description
Enabled Specifies whether the rule is enabled. If a rule is not enabled it will be ignored by Hurricane MTA Server.
Priority Specifies the ordinal position of the rule in the list. Rules are evaluated from top to bottom until a match is made. 1 is the highest priority.
Match A regular expression that will be matched against responses from the ISP being handled by the Delivery Rule. If a match is made, the rule will be activated.
Action Possible values: Alert Only – Generate an alert, but do not alter delivery Defer – Defer all mail to this ISP for the specified Duration Fail – Fail all mail to this ISP for the specified Duration
Duration Number of minutes this rule should remain in force once activated. This value is ignored if Action is set to “Alert Only”.

So what are some of the reasons why an ISP would want you to stop delivering mail? This could be the result of sending too much mail per hour, receiving too many complaints about your email, trying to deliver to bad email addresses or various other reasons. The important thing is that the ISP wants you to pause sending and failure to do so can damage your reputation. The Dynamic Block Rule system is a part of the latest release of Hurricane MTA Server. There is also a new Dynamic Block Rule log file that can be enabled via the log settings for each account. A future post will outline that log file and show you how it can be used to analyze the effectiveness of your Dynamic Block Rules and and fine tune them to obtain the highest deliverability possible. Within the next month we will incorporate block rules into Hurricane MTA Server’s Smart Delivery Rule list. Smart Delivery Rules are a set of Delivery Rules defined and periodically updated by SocketLabs to properly shape traffic to the large ISPs. Until then, you can try your hand at creating your own Dynamic Block Rules to get a feel for how the system works.

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