It's in the mail, or is it?
By Research Fellow, Peter Slattery [updated 20/10/22]
At BehaviourWorks, we’re often asked: “Should we send emails or letters?”
There isn’t a right answer to this question – it always depends on the factors at play.
In this article, we explore some of these factors to help you to make better decisions. After that, we discuss persuasive strategies for written communication.
Letters and emails are different communication channels with different qualities.
To make these qualities clearer, let’s compare letters and emails in three ways:
Compared to emails, letters can, for example:
Here are three relevant differences in how people engage with emails and letters.
First, when people open letters, they are usually focusing all attention on the letter. In contrast, when people open emails, they are more likely to be distracted. For instance, they may be aware of other emails on their screen.
Second, people have consistent expectations of the length of letters. Letters are usually one size. The letter-opener is therefore prepared to read a full letter when they get one. An unopened letter won't appear to be longer if we add a persuasive strategy. Usually it will be opened and read just as much.
In contrast, people vary more in their expectations of the length of emails. Short emails are common and emails don't come in a standard window, so their length is even more noticeable. If emails are longer, then the reader needs to scroll down the screen to get through them. The reader is therefore more likely to ignore or abandon longer emails.
Third, people open emails based on the source and subject line. People will be much more likely to read your email if it comes from a good and credible source, than if it doesn't. In contrast, letters give you much less information about who they are from or what they are about before they are opened.
There are many different metrics for assessing how communication is performing. With letters, you can measure outcome factors, such as:
With email, you can often measure more outcomes, such as:
In general, it is easier to measure metrics for email than for with letters. This is an important consideration for pilot-testing, monitoring and evaluation. For example, with email you can often track the percentage of intended receivers who:
This is not usually possible with letters.
Compared to emails, a higher percentage of letters are opened and responded to. But that doesn't answer our main question. We still don't know if letters change behaviour at a higher rate than emails.
Letters cost significantly more to send than emails, but do they return on that investment? There doesn’t seem to be a good research on this. However, some sources suggest that email is more cost-effective.
All the identified comparisons between letters and emails were quick summaries. All failed to control for confounding factors. We cannot therefore be sure that differences in outcomes were due to the channels used. Instead, they may be due to differences in the behaviours and populations targeted.
These are some of the implications when choosing between letters and emails:
You can harness the benefits of both emails and letter by using both together:
Adding a persuasive technique to an email is somewhat riskier than adding it to a letter. The new content may be persuasive in insolation. However, the email’s increased length may cause potential readers to ignore the email or stop reading it. Be especially cautious if your email is already long or your readers are busy.
When writing emails, it becomes more important to think about what the receiver will see for the source of the email, and the subject line.
At BWA, we developed a framework called INSPIRE. This framework make it easier to include persuasive strategies within written communication.
The INSPIRE framework outlines several techniques that improve the impact of written communication. Other frameworks, such as EAST, are also widely used.
So, should you send emails or letters? It still depends, but perhaps you now have a better sense of what it depends on – and why. What do you think of the letter and emails? What is your favourite behaviour change framework?
To learn about behavioural science, please check our other award-winning content, and free book. Please see this course if you are interested in learning more about INSPIRE.
To ask me to explore other behavioural science questions, please email: peter.slattery@monash.edu
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