Released in June 2008, Alchemy Worx's study of over 600 subject lines across 200 million messages shows an unexpected relationship between click-to-open rates and subject line length, suggesting very strongly that past subject line analysis may have led email marketers seriously astray.
In order to provide insight into what subject lines work best, our deep analysis examined the data in a granular way and added an additional level of sophistication to previously released reports. Instead of grouping subject lines into two categories, we used 13 groups of 10 characters (11-20, 21-30 etc) and also investigated the effect of subject line length on the number of words and click-to-open rates as we believe they provide a better indication of relevance - and after all, is an open without a click really a measure of success? Highlights include:
- Subject lines of less than 60 characters proved best for optimizing open rates
- Click and click to open rates are optimized by longer subject lines
- A dead zone of subject lines was identified, where neither metric is optimized.
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