Email subject line performance

I came across a very interesting study showing email effectiveness, both by open rate and click through rate, by email subject line. Obviously I experiment a lot with email performance, varying subject line, content, design, etc. But it’s great to see data aggregated across a large number of campaigns.

The study was done by Adestra and is available here. Based on billions of sent messages from b2b companies, the looks at performance of different subject lines. I’m just going to quote from solid Marketingchart write up on the study, as it is very interesting data (the following is a direct quote):

  • Currency symbols: Subject lines containing the £ symbol had a far better-than-average (57.8%) click-to-open rate. Those with $ signs scored above-average in opens (15.7%) and clicks (14.7%), but slightly below-average in click-to-opens (-0.8%). Subject lines containing the € symbol were above-average in opens (2.9%) but below-average in clicks (-8.2%) and click-to-opens (-10.8%). Of course, targeting has a big effect on this – as some symbols may be irrelevant to the recipient.
  • Discount terms: These generally performed below-average. “Sale” was the outlier, above-average in opens (14.4%), clicks (76.5%), and click-to-opens (54.3%). Others such as “% off,” “discount,” “free,” “half price,” “save,” “voucher,” “early bird,” and “2 for 1″ all came in below-average in all 3 metrics, save for “voucher,” which had above-average opens (6.5%). “Early bird” was the worst performer in terms of clicks (-71.6%) and click-to-opens (-67.6%).
  • News terms: These had better success than discount terms. “News” (16.2%), “update” (4.9%), “breaking” (33.5%), “alert” (25.9%), and “bulletin” (12.5%) all saw better-than-average click-to-open rates (as well as clicks and opens), with “newsletter” being the only term to perform below-average in each metric. “Alert” saw the best differential for clicks (78.3%), while “news” did best for opens (30.9%).
  • Content terms: There were more discrepancies in this theme. “Issue” (8.5%) and “top stories” (5.9%) were the only to perform above-average in click-to-opens, although the latter saw slightly below-average open and click rates. “Forecast,” “report,” “whitepaper,” and “download” all saw below-average performance in each of the 3 metrics. “Research,” “interview,” and “video” scored above-average for opens, but below-average for clicks and click-to-opens.
  • Benefit terms: “Latest” was the only to see above-average clicks (8.8%) and click-to-opens (9%), while “special,” “exclusive,” and “innovate,” while performing about average in opens, fared far more poorly in clicks and click-to-opens.
  • Event terms: Each of these terms performed below-average in opens, clicks, and click-to-opens. The terms examined were: “exhibition,” “conference,” “webinar,” “seminar,” “training,” “expo,” “event,” “register,” and “registration.” The worst offender for click-to-opens was “webinar” (-63.5%).
  • Multichannel terms: Facebook (21.6%) and Pinterest (16.4%) were the only terms to score above-average in clicks and click-to-opens, though both showed below-average performance in opens. On the flip side, “app” and “iPad” were above-average in opens, and below-average in clicks and click-to-opens. Both “Twitter” and “LinkedIn” were below-average in all 3 metrics.

Some of the take aways are likely to be correct for many email marketers, regardless of industry. The low performance of words like “webinar” and discount terms is probably something most marketers will see with their email campaigns. But it’s pretty hard to say that currency symbols will perform for everyone.

I guess the usual summary is that it makes sense to aggressively test all of this!

Author: Healy Jones

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2 Comments

  1. Some really great details here. I wouldn’t have guessed that ‘webinar’ would score so low, but it makes sense. With so many competing for attention through webinars now, it’s easy to sign up, and just as easy to ignore the reminders and promos depending on one’s schedule and priorities.

    Post a Reply
    • Yes, I was pretty impressed with the level of detail in the analysis.

      I guess webinar is a little over-used at this point. I don’t have that much time for random newsletters that I hear about via email, and I haven’t had a ton of luck promoting webinars over email either… maybe there is a better way to promote webinars than email!

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