A recent study conducted by email marketing firm Adestra offers some interesting, and perhaps surprising, insights into how email subject lines affect user engagement metrics.
The study, which involved a random sample of the firm's email campaigns, analyzed click-through, open and click-to-open rates for 932 million emails during a six month period. The study broke out specific market segments, including e-Commerce, event marketing, and charities; it also compared B2B versus B2C response rates.
For B2B email subject lines, the study found that longer subject lines tend to deliver much higher click-to-open rates, versus the industry average. "Quite simply, the more words the better for the B2B sector," states the report. "Subject lines with 6-10 words drive open rates but don't deliver the resulting click-throughs. Consider these for awareness emails that don't necessarily have a direct call to action to click. Anything over 16 words, however, can deliver on both [open rates and click-throughs]."
The study drew a similar conclusion about the ideal length for B2C email subject lines: "A 20-word subject line appears to be a clear winner, delivering a massive 114% uplift in open rates and 85% uplift in clicks."
The Adestra study also looked at which specific words have the greatest impact on email metrics. Some words that do well in B2C subject lines, including "free" and "exclusive," actually depressed B2B email click-to-open rates. For B2B emails, words such as "profit," "revenue" and "turnover" had the greatest impact.
The report also noted that words actually used to describe the B2B sector tend to have a negative impact on email metrics. "Take the word 'B2B' as an example which causes open and click-through rates to crash through the floor," stated the report. "The words 'business' and 'industry' have the same effect."
The report speculates that B2B subject lines benefit from more specific terminology: "These terms are too specific for such a broad sector…focus instead on your industry's colloquialisms and the results will follow."