In a digital age where electronic channels have revolutionised the way in which we stay connected it is no surprise that marketers are heavily debating whether to favour direct email over direct mail. Although statistics in favour of or against both channels is easy to find, a balanced and objective view is harder to come by. Go Inspire Insight has therefore drawn data from a large-scale randomised control trial (RCT) to help assess the statistics and make sense out of all the ‘noise’.

4.4 billion pieces of direct mail are sent every year in the UK[1]. By comparison, the UK’s leading direct email benchmarking report analyses 37 billion emails – and this is only a significant sample of the total. Click-through rates are 1.56% for direct marketing email, compared with average response rates for direct mail of 4.4%[2].

Among the wide availability of statistics, the consistently comparable measurements of performance have not been examined. Therefore, Go Inspire Insight conducted a RCT in order to put the relative performance of direct mail and direct email to test on an equal playing field.

In order to settle the debate, equal effort was applied to both channels in all aspects: segmentation, timings and creative variants. The RCT consisted of a single campaign that was mounted for a retail client. To ensure a meaningful outcome it was imperative that the products offered by the client had a broad market appeal to customers of all genders, income levels and geographic locations across the UK.

240,000 customers participated in the RCT and were categorised into three randomised segments. The measurement of success was dependent on the incremental revenue generated rather than response rates. One randomised segment of the distribution database received offers by post alone. Another received the offers only over email. Finally, the third segment received the offers via both channels.

The outcome was revealing. Whereas response rates remained in a similar range, conversion and incremental revenue rates delivered clearly diverging results. Those who only received offers by email generated incremental revenue per customer of under £1, those who received the offers only through postal direct mail generated an incremental revenue per customer of around £5 and those who received the offers through the post and by email generated incremental revenue per customer of over £6.

Clearly, the results of this RCT show that commercial outcomes (rather than just campaign response) differ widely between standalone email and standalone postal mail. However, the real learning for modern marketers is the power of both media in tandem, and the fact that the combination adds

the power of each together to provide a stronger commercial output where neither medium is cannibalising the other.

The overriding message from this study is that marketers should not be pitting direct mail and direct email as an either/or decision but should explore ways in which a combination of both channels can deliver the most successful, incremental and complementary effect.


[Source: Andy Wood, Chairman, Go Inspire Insight]

[1] DMA, Email benchmarking report 2017

[2] DMA, Email benchmarking report 2017

By Alison