According to Yes Lifecycle Marketing, e-mail volume was up 18% year over year in 2017, however, the number of people signing up for e-mail subscriptions steadily declined throughout the year. After analyzing more than 30 billion e-mails sent last year, the e-mail marketing platform has released a benchmark report looking at a number of data points around e-mail marketing volume, engagement and design.

New subscriber e-mail trends

Among the many findings, brands are sending more and more e-mails, but new subscribers’ share of their lists continued to shrink last year.

“Throughout 2017, the share of new subscribers in marketers’ databases consistently declined, falling to its lowest point in Q4 when new subscribers accounted for just 3.5% of marketers’ mailable audience,” reports Yes Lifecycle Marketing.

Subscribers opting in within 90-days

Yes Lifecycle Marketing says, the share of new subscriber numbers included in marketers’ databases usually lifts between Q3 and Q4 but last year “marked a U-turn” in this trend.

In addition to the share of new subscribers growing smaller throughout the duration of 2017, 20% of brands’ mailable audiences hadn’t opened an email in more than a year — representing a 22.5% year-over-year jump in inactive subscribers. Open rates per subscriber did show some growth — with unique opens up 8.4% year over year.

Mobile e-mail marketing results

Yes Lifecycle Marketing’s data revealed mobile e-mail conversion rates have caught up to desktop conversions, with both at an average of 3.3% for the year. It also claims e-mail adoption on mobile may have hit its peak. According to the report, mobile e-mail marketing events – open rates and clicks – surpassed desktop events at least five years ago. In 2017, 52.9% of events happened on mobile e-mail versus 47.1% on desktop. Orders on mobile represented 46% of all e-mail-driven orders — a 33% increase year over year. Meanwhile, e-mail orders happening on desktops dropped 18%.

As e-mail-driven orders rise on mobile, the report says the average order value (AOV) for mobile orders remains 40% less than for desktop orders, with AOV on mobile at $58 compared to desktop’s $96 AOV. According to Yes Lifecycle Marketing, this mobile-to-desktop AOV ratio has not changed during the past three years.

Responsive design impact on e-mail marketing

The report examined how responsive design — the design format that automatically adapts an e-mail to the screen size — impacts e-mail marketing performance. It found brands that always send responsive design e-mail messaging perform better on both desktop and mobile. For the brands that only used responsive design, their CTO (click-to-open) rate for desktop e-mails was 13.1% and 13.2% for mobile. Brands that failed to use responsive design saw only a 9.7% CTO rate for both desktop e-mails and mobile e-mails.

Even more interesting, the brands that were inconsistent with their use of responsive design, using it only some of the time, performed the worst when looking at combined numbers for desktop and mobile open rates.

According to the data, brands that always use responsive design earned a 15% open rate (for desktop and mobile combined), and brands that never used responsive design earned a 14.9% open rate; but brands that were inconsistent with their use earned a 13.5% open rate.

The report says only 24.2% of the brands it evaluated used responsive design all of the time. The biggest share of marketers, 60.9%, was the group that uses responsive design some of the time. Only 14.8% of the brands never used responsive design.

E-mail subject lines

Yes, Lifecycle Marketing took a deep dive into subject lines, breaking down performance analytics based on the offers listed in the subject line of an e-mail. It found 23% of all the e-mails analyzed in 2017 included an offer in the subject line, with more than half (54%) using a “% off” message.

Loyalty offers generated the highest scores across the board for open rates, unique click rates, CTOs and conversion rates — which adds up since they are going to a select audience that already has a relationship with the brand. The “$ Off” offers were a close second for conversion rates, scoring 10.2% compared to the loyalty incentive-driven offer email’s 10.8% conversion rate.

Success rates based on email subject line offer types

According to the data, subject lines that include offers — “Free Shipping” or “$ Off” — generate four times the conversion rate of emails that do not have subject lines around offers, but they earn much less engagement, with only a 2% conversion rate.

“The true bar for both engagement and conversion is set by standard emails that do not contain any offers in the subject line,” writes Yes Lifecycle Marketing. “Those emails drive considerably higher engagement than messages with offers, in fact, they generate 35% high[er] open rate, 50% higher CTO, and double the unique click rate.”

Triggered e-mail campaigns

Yes Lifecycle Marketing says triggered campaigns executed during Q4 2017 earned more than double the open rate, more than triple the number of unique click rates and nearly double the CTOs compared to standard e-mails. Unfortunately, only 2.3% of the e-mails it evaluated were part of a trigger campaign — a number that remained the same throughout all four quarters of the year.

Performance of standard versus triggered e-mails

The report looked at the different types of trigger campaign messaging and found “Welcome” messages generated the best open rate at 29% compared to the 13.4% open rate for standard e-mails. Other trigger e-mail types like “Activation,” “Anniversary” and “Birthday” e-mails earned a 17% open rate.

For conversion rates, the best-performing trigger e-mail campaign was an “Anniversary” e-mail, which generated an 8.5% conversion rate compared to a standard e-mail’s 4.8% conversion rate.

Performance analytics for trigger e-mail campaigns

Along with a number of e-mail marketing benchmarks, the report also included case studies around campaigns that performed well to highlight successful e-mail marketing campaigns. Throughout the report, Yes Lifecycle Marketing listed a number of ways brands could be taking advantage of their e-mail marketing, outlining “prep” work and goals for Q4 2018.