Spam filters can make the life of an e-marketer very difficult. Certain words get more negative scores than others when these filters are doing their job. That ‘Viagra’ is an alarming word in an email message, is clear.
But a word like ‘free’ is more difficult. We want to spoil our email contacts in our mailing list with an offer. The American HubSpot thought the same thing. They did an experiment and got to an interesting conclusion.
They wanted to know if the word ‘free’ swayed all the red flags of the spam filters. They sent an email to a part of their audience with an A/B test. Version A got the subject line ‘Free guide…’ and the word ‘free’ was repeated several times in the body text as well.
In version B the word ‘free’ was banished completely and the subject line was changed to ‘SEO guide’. With the campaign they wanted the answer to 2 questions. Will the word ‘free’ damage’ my delivery rate? And will that make a difference in my open and click rate? The answer was surprising.
We can be short about the delivery rate. Version A survived 7 of the 9 spam filter in their spam check, and was delivered to 99,3% of the recipients selected by HubSpot. Version B, without the word ‘free’ got through 8 of those 9 spam filters and got delivered to 99,2% of the segment. In other words, hardly any difference.
Can we go ahead with our free offer then? Apparently not. Because what was the surprising conclusion? Version B, with the ‘SEO guide’ in the subject line was the clear winner in the clicking behaviour. HubSpot detected an increase of 17 per cent compared to the version of the free ‘free offer’. And that is important.
So what is the moral of the story? Single words are no longer immediately dangerous according to the spam filters. These have become a lot more intelligent and take a look at the context as well. Terms like ‘free’ will pass undisturbed when your content is serious and your reputation ok. But the reader does not always seem to be sensitive to the word free. Continued testing can be very important!