Relationships Between Email Volume, Time and Response Rates

There appears to be an appreciable relationship between the time at which businesses send out emails, volume of emails, and the response rates they receive.

According to a 2013 Email Marketing Industry Census by Econsultancy / Adestra, only 49% of email marketers are testing the relationship between time and email response rates. There are a number of studies which suggest strong correlations between these two factors, and a recent Experian Marketing Services study run on Q4 of 2013 adds to the bevy  of evidence which supports this relationship. The industry census also demonstrated significant correlations between email volume and response rates.

The Experian study revealed that brands sent 27% of emails from 4AM to 7:59AM, and 35% between 8AM and 11:59AM. These two time periods claimed 33% (each) of total transactions. The 4AM to 7:59AM time period had the lowest unique open rate (16.8%) and shared the lowest unique click rate with the 8AM to 11:59AM slot (2.3%).

In addition to this low unique click rate, the 8AM to 11:59AM time interval also had the lowest transaction rate (0.07%) and the lowest revenue per email ($.09). Although weak in response rates, the 8AM to 11:59AM slot had the highest average order value ($192). Moving to different times of the day, the 8PM to 11:59PM and 12AM to 3:59AM slots accounted for the lowest percentages of total volume, at 3% and 9%, respectively. Although it had the lowest email volume, the 8PM to 11:59PM interval had the highest unique open rate (22.7%), unique click rate (3.6%), transaction rate (0.22%) and revenue per email ($0.23). The 12AM to 3:59AM slot, which had the second lowest percentage of volume, came second highest in unique click rate (3.4%), transaction rate (0.17%) and revenue per email ($0.20).

Source: An Inverse Relationship Between Email Volume and Response Rates?,  MarketingCharts (March 4, 2014)

The relationship between time and response rates holds across days of the week as well. Tuesday, Thursday and Friday all accounted for the highest percentage of total email volume (16% each) yet shared the lowest transaction rate with Wednesday (.07%). While Friday was among the days with the highest email volume, it had the lowest unique open rate (16.9%), unique click rate (2.2%) and transaction rate (0.07%).

Saturday had the lowest email volume (10%), however claimed the highest unique open rate (18.3%), second highest unique click rate (2.5%), shared the highest transaction rate with Sunday (0.09%), had the second highest revenue per email ($0.12) and the highest average order value ($201). Sunday had the second lowest email volume (12%), yet the highest unique click rate (2.7%), highest transaction rate (0.09%) and highest revenue per email ($0.13). Despite good response rates, Sunday had the lowest average order value ($174).

Source: An Inverse Relationship Between Email Volume and Response Rates?,  MarketingCharts (March 4, 2014)

There appears to be an appreciable relationship between the time at which companies send out emails and the response rates they receive. Although the Experian study offers clues as to why this occurs, there is not enough data to imply causation between email volume and response rates. Consumers may e.g. be more busy during the times at which email volumes are high. The better response rates of lower email volume Saturdays vis–à–vis higher volume Sundays could be attributable to the lassitudinous nature of Sundays in comparison with Saturdays among certain demographics. In conclusion, email marketing campaigns may stand to benefit from employing temporal factors in their strategy but should consider adding precision to their timing by incorporating other considerations (e.g. behavioral) into the quantitative relationships observed between time, volume and email response rates.

Sources:

1)  2013 Q4 Email Benchmark Study - Experian Marketing Services

2) An Inverse Relationship Between Email Volume and Response Rates?,  MarketingCharts (March 4, 2014)

3) Email Marketing Industry Census 2013, Econsultancy (April 2013)