/ Resources
Emails vs letters. What works, when and why

Emails vs letters. What works, when and why

It's in the mail, or is it?

At BehaviourWorks, we frequently work on projects where large numbers of people or key stakeholders need to be contacted and we’re often asked: “Should we send emails or letters?”

By Research Fellow, Peter Slattery

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 and how, by gaining a better understanding of them, you can make better decisions.

If you would like to know more about behavioural science research and practice then please check our other award-winning content, and free book.

Comparing emails and letters

Attempts at behaviour change succeed or fail in relation to the interaction of different categories of factors (for more details see my, paper and post article or some of the communication models that it builds on).

From this perspective, letters and emails are different communication channels, with different qualities and their suitability for a specific communication opportunity depends on the other factors involved.

To make these factors clearer, let’s compare letters and emails in three ways:

  • i) what they can do (that the other can’t),
  • ii) how we engage with them, and
  • iii) what they achieve.

What each can do (that the other can’t)

Compared to emails, letters can, for example:

  • Reach target audiences that don’t have email.
  • Have a tangible physical ‘presence’ that will hold attention for longer.
  • People often keep letters for months, while emails are processed and forgotten immediately.
  • Gain appreciation or prompt a desire to reciprocate because they signal the sender has invested more effort in contacting them.
  • Provide simpler information that is easier to process and less-distracting.
  • Length is also much more salient online. Our cues for letter length are the number of pages. One page, with white space in the middle, doesn’t feel that much longer than a page with a little less white space.
  • In contrast, it is very noticeable when emails extend below the bottom of our screen or we have to scroll to read them.

What do they achieve?

There are many different metrics for assessing how communication is performing. With letters you can measure outcome factors, such as:

  • Reception rate – did people get the letter?
  • Open rate – did they open the letter?
  • Recall rate – did they remember the letter.
  • Response rate – did they respond to the letter?
  • Compliance rate – did people do what the letter asked.

With the email you can often measure additional outcomes, such as:

  • Read rate – did they read the email?
  • Read time – how long did they read the email?
  • Click rates – how many people clicked a link?

In general you can also measure metrics for email more easily and automatically than you can with letters – an important consideration for pilot-testing, monitoring and evaluation. For example, you can often easily track the percentage of intended receivers who:

  • i) received the email
  • ii) opened
  • iii) engaged with
  • iv) shared it, and
  • v) acted because of it.

So, how do letters and emails compare when tested on similar outcomes?

Compared to emails, a higher percentage of letters are opened and responded to. While it therefore appears that more people receive and reply to the information sent by letter, this information does not show that letters necessarily change behaviour at a higher rate than emails, particularly if the behaviour targeted requires doing something online.

What about cost-effectiveness?

Letters cost significantly more to send than emails but do they return on that investment? There doesn’t seem to be a lot of good research on this. Some sources suggest that email is more cost-effective.

It is crucial to note that, all of the identified comparisons between letters and emails were quick summaries which failed to control for confounding factors. The differences in outcomes might not be due to the channels used and instead, be due to differences in the behaviours and populations targeted.

The results also probably change every year because we increasingly get fewer letters and more emails.

So, what are the implications?

The differences between emails and letters have many implications for communicators, for example:

  • Because letters are less cost-effective than emails, it may be best to reserve them for specific situations.

For instance, critical or time-sensitive communications, or cases where email cannot be used.

Email may be particularly suited to convey complex and lengthy information by linking out to relevant information.

Using emails and letters in combination as part of sequenced communication can harness the benefits of both:

  • To save costs, the first wave of emails can prompt a response from all supportive parties, while a follow-up letter can convert those who missed the email.
  • Urgent, financially unconstrained campaigns can send letters and emails at the same time to ensure that as many people as possible are notified at least once.
  • The differences between emails and letters also influence how you should plan to use persuasive techniques.

At BWA, we developed the INSPIRE framework (below) to capture and make these strategies more visible.

INSPIRE outlines several techniques that improve the impact of written communication. Other frameworks, such as EAST, are also widely used.

While these and other persuasive techniques also work via email, their use needs to be planned differently. For example, adding an extra line with a persuasive technique to a letter may make it more effective assuming it maintains the page length.

In contrast, there may be more downside attached to adding the same persuasive techniques to an email. While seeing the new line may remain persuasive, readers’ perceptions of the email’s increased length may also make it more likely that they will choose not to engage with that email.


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?

What other behaviour change questions would you like me to explore? Email: Peter.slattery@monash.eud


  1. https://www.smallbizgenius.net/by-the-numbers/direct-mail-statistics/#gref
  2. https://www.tandfonline.com/doi/full/10.1080/0144929X.2019.1685594
  3. https://www.billprint.com.au/mail-house/email-vs-direct-mail
  4. https://www.snap.com.au/blog/research–direct-mail-vs-email—which-performs-best-5
  5. Examining the online reading behaviour and performance of fifth-graders: evidence from eye-movement data
Education & training

Looking to upskill?

Check out our Monash University accredited courses, along with our short and bespoke training programs.


Have a project for us?

We offer a broad range of research services to help governments, industries and NGOs find behavioural solutions.


Explore our resources

We believe in building capacity and sharing knowledge through multiple channels to our partners, collaborators and the wider community.


Sign up to the broadcast

Get monthly behaviour change content and insights