7 Ways to Improve Your Email Deliverability
By Tim Watson @eMarketeers 2/1/12
When companies approach me with deliverability issues I often find they are looking in the wrong place for the cause of inbox placement issues. Typically the conversation begins with my client’s perceived need to get an audit of their sending infrastructure, email HTML and content.
Whilst these can affect inbox placement, the problems normally lie elsewhere. So I’m providing in this post the top 7 causes that can stop you getting to the inbox and you will learn the relative importance of each.
Layered spam filtering
The ISPs take a layered approach to deciding whether an email should be placed in the inbox or not. These layers have been built up over years of refinement, so a quick look at the evolution of spam filtering is valuable to understand how they work.
In the early days (pre-2000), a technically valid configuration was the key factor. If your email server and DNS were set up correctly to Internet standards, that went a long way to show you were a legitimate sender, enabling emails to be successfully delivered to the inbox.
Next came whitelisting; ensuring your IP address was whitelisted as a good sender helped inbox placement.
Since spammers could easily make sure they also followed standards, and whitelists became unmanaged to provide any manual validation, ISPs turned to content based filtering: using words and phrases often used in spam emails could land you in the junk folder. Spammers tried to disguise their content by deliberate misspellings, or by placing text content in images where computer filters could not see them.
Many potential spam words also occurred frequently in legitimate emails. A better method was needed.
The ISPs came up with the smart idea of using the judgement of their customers to determine what was spam. If many customers hit the junk email button for a particular email, then the ISP considers that email to be spam. So sender reputation was born. The sending IP address and sending domain are given a reputation based on spam complaints, email bounces and spam traps.
Judging spam based on user behaviour has been very successful at filtering spam, as, unlike other methods, its difficult for spammers to falsify. The ISPs are further enhancing filtering based on user behaviour by looking also at engagement; for example, forwarding, replying and reading. These are not actions users do with spam emails.
Whilst reputation and engagement are the most important factors, none of the other layers have gone away. (continue @eMarketeers)