Case Study: Penetrate More Inboxes With The Right Email Length

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The objective of this case study was to analyze the impact of email length on open rates and click-through rates in a cold email campaign. The study aimed to identify the relationship between email length and recipient engagement.


A cold email campaign was conducted, targeting a specific audience segment. The campaign involved sending emails with varying word counts.

The emails sent can be viewed here.

Each email variant was randomly sent to a subset of the target audience, ensuring equal representation for each email length.

Open rates and click-through rates were measured and recorded for each email length, and the data was analyzed to identify trends in recipient engagement.

How To Send Cold Email


The study produced the following results for open rates and click-through rates based on different email lengths:


No Of Words
Open Rate
Click Through
761 words40.00%18.00%
569 words44.00%14.00%
245 words50.00%13.00%
209 words49.00%15.00%
192 words40.00%17.00%
179 word43.00%15.00%
155 words42.00%14.00%
144 words45.00%18.00%
112 words49.00%19.00%
98 words50.00%19.00%
90 words47.00%16.00%
87 words47.00%17.00%
46 words40.00%13.00%
42 words43.00%15.00%
34 words42.00%10.00%
26 words39.00%9.00%
19 words41.00%10.00%


Based on the data collected, a correlation can be observed between email length and recipient engagement in terms of open rates and click-through rates. However, the relationship is not necessarily linear, and there are variations in engagement across different email lengths.

While shorter emails tend to have higher open rates, there is no consistent pattern for click-through rates. Some shorter emails performed well in terms of click-through rates, while others did not.

In terms of open rates, emails in the range of 209 to 569 words performed relatively well, with open rates ranging from 44.00% to 50.00%. Click-through rates were more varied, but some email lengths, such as 112 words and 98 words, achieved higher engagement.

Interestingly, extremely short emails (e.g., 26 words or less) showed lower open rates and click-through rates compared to other lengths, suggesting that they may lack sufficient information or context to capture recipient interest.


Based on the findings of this case study, it can be concluded that the relationship between email length and recipient engagement is complex. While shorter emails generally perform well in terms of open rates, click-through rates may vary. The study indicated that two groups had optimal engagement: 209 to 569 words and also 98 words and 112 words.

The results confirmed my belief that 100 words would be the “sweet spot” for this type of email

What Surprised Me

The fact that there was not really one clear winner. Two different groups both had virtually the same results (209 to 569) and the much briefer (98 to 112) words. I think that this can be explained by the event that I was promoting. People seemed to respond well to receiving more detailed information about the event. For different types of campaigns, you may not see this result duplicated.

It is important to consider other factors such as content, personalization, and value proposition in conjunction with email length to optimize recipient engagement. Testing different email lengths within your specific target audience is recommended to determine the most effective approach for your cold email campaigns.


The results of this case study are specific to the tested audience and may not be universally applicable. It is recommended to conduct similar experiments within your own target audience to determine the most effective email length and optimize recipient engagement for your specific cold email campaigns.

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