Does email personalization work? What the research says

Two large studies of millions of emails show when personalization lifts opens and leads, and when it backfires. Lessons for B2B cold email.

3 min read ·

Short answer: yes, when the recipient finds it relevant. Two large academic studies of millions of emails give answers that look contradictory at first. Read together, they offer a clear lesson for B2B cold email.

Study 1: A name in the subject line lifted opens

Navdeep Sahni, S. Christian Wheeler (Stanford) and Pradeep Chintagunta (Chicago Booth) ran randomised field experiments with three organisations, sending tailored emails to millions of people. One partner sold exam-prep courses to finance professionals.

In the main experiment, adding the recipient’s name to the subject line produced:

Measure Result
Probability of opening Up about 20% (from roughly 9% to 11%)
Sales leads Up about 31%
Unsubscribes Down about 17%

The researchers argue that the name adds no information about the product, but it makes recipients pay more attention to the rest of the message. A notable side finding: at the exam-prep company, a discount offer increased leads only when the email was personalised.

Study 2: Greeting people by name can backfire

Sunil Wattal and colleagues at Carnegie Mellon analysed more than 10 million email ads sent by an online merchant to over 600,000 customers. The result seems to contradict the first study:

  • Product-based personalisation (showing products the customer likes) was received positively.
  • Explicit use of personal information, such as a greeting by name, was on average received negatively.
  • The negative effect depended on familiarity with the firm: customers who did not know the company reacted most negatively.

The authors link this to privacy concerns: when people notice how their information is being used, they become wary.

Reading the two studies together

Both studies point the same way: personalisation works when recipients see it as natural and relevant. When the sender is unknown and personalisation is just a shallow greeting with the first name dropped in, it can feel like a line has been crossed.

These studies were run on B2C and marketing emails, not B2B cold outreach. Still, the logic transfers:

  1. A name alone is not enough. It may catch attention in a subject line, but the body must say something genuinely relevant about the recipient’s company, role or problem.
  2. Relevance beats a name. One sentence about the prospect’s sector, growth stage or new market does more than their first name.
  3. Be measured with people who don’t know you. In cold email the recipient has never heard of you. Use business context, not personal details: public signals like company news, job posts or product launches.
  4. Test it. Try subject lines with and without the name on your own list. Research shows a direction; only your test shows your market’s answer.

At ArgonOut Global, every message in our cold email outreach campaigns is written around the target company’s public business signals, and subject lines are tested market by market.

FAQ

Does adding a name to the subject line increase open rates?

In Stanford’s field experiment, adding the recipient’s name to the subject line raised the probability of opening by about 20% (Sahni, Wheeler & Chintagunta, 2018). Effects vary by market and audience, so test on your own list.

When does personalisation backfire?

In Wattal et al. (2012), recipients unfamiliar with the sender reacted more negatively to emails that greeted them by name. Shallow or irrelevant personalisation can trigger privacy concerns.

References

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