Como escrevemos linhas de assunto de e-mails frios que obtêm resultados concretos

Um blog convidado de Will Cannon (fundador e CEO da UpLead)

Writing cold emails that get opened, let alone convert, is very challenging, simply because you’re sending those to strangers. Without an established relationship with your cold targets, it’s easy to get frustrated: there’s zero feedback and your emails are usually sent to the spam folder.

There are a lot of factors that influence the success of your cold emails. Arguably the most important is the subject line. It directly influences the open rate, click-through rate, as well as conversion. That’s why you must ensure your subject lines are of high quality. 🥇

Neste artigo, abordaremos:

  • A função que as linhas de assunto desempenham em seu alcance de e-mail frio
  • Mais de 4 exemplos de práticas recomendadas respaldadas por dados

Ready? Let’s get started. 👇

Função das linhas de assunto em suas campanhas de e-mail frio

Subject lines play an important role in any email campaign, warm or cold. They’re the first impression of your emails; it’s the first thing your targets see of them. When they open up their inbox, they judge what you’ve sent them based on the subject line you’ve written.

Subject lines are more essential for cold email, simply due to the impersonal nature of emailing strangers. You must also consider that the people you’re targeting aren’t on your email list. This means that, when targeting US citizens, the CAN-SPAM Act is especially important. ⚠️

If you didn’t know, the CAN-SPAM Act is a law that governs the rules surrounding commercial email, especially bulk emailing. Regarding email subject lines, the law specifically states:

Don’t use deceptive subject lines. The subject line must accurately reflect the content of the message.

Even though The CAN-SPAM Act is for both warm and cold emailing, it’s probably more significant for cold. Most email marketing tools for warm emailing have safeguards in place to warn you of these types of mistakes, but cold email platforms typically don’t. This is something to seriously consider whenever you send prospective sales/marketing emails to targeted strangers.

Simplificando: É importante ter uma lista de endereços de e-mail válidos para o alcance de seu e-mail frio e o objetivo de uma linha de assunto é fazer com que o alvo/leitor abra o e-mail. Isso é muito importante no envio de e-mails frios.

Mais de 4 práticas recomendadas para linhas de assunto (respaldadas pela ciência)

Below, you’ll find 4+ different best practice strategies you can use to improve the subject lines of your cold emails. Each will include some real, visual examples; that’ll help you understand how to effectively implement them.

OBSERVAÇÃO: You won’t be able to use all of these together at once. Some of them are appropriate for certain emails and contexts, where others are not. Consider all of the strategies outlined below as tools in your toolbelt.

1. Personalize as linhas de assunto de seu e-mail

Did you know that emails with personalized subject lines have a 22.2% greater chance of being opened? This isn’t surprising in the least: personalizing your email subject lines makes them far more effective; warm or cold.

But why is this? 🤔

People love to hear or read their own names, or at least something personal to them. It was Dale Carnegie — author of How to Win Friends and Influence People — who once said:

A person’s name is to that person, the sweetest, most important sound in any language.

Does it need any more explanation than that? If you received two emails with identical subject lines, except for using your name, which one would you open first? Exactly: personalization works because… it’s personal — and so is email messaging.

So, how do you personalize your email subject lines? There are several different methods you could try, including the most obvious: simply using their name. Here’s a list of ideas you can potentially use:

  • Use o primeiro nome ou o nome completo da pessoa
  • Usar o nome da empresa em que trabalham
  • Use seu cargo

O grau de personalização que você pode obter será limitado aos dados que você tem sobre eles. Um bom banco de dados/lista de contatos o ajudará a encontrar informações relevantes.

To personalize a step further, you could search them up on LinkedIn. It could tell you that they attended a conference, event, or workshop. It could also tell you what articles they’ve read, liked, or even written. If they’ve got social media profiles, check them out.

If implemented correctly, here’s how it could look:

2. Mantenha as linhas de assunto de seu e-mail curtas

Another tactic you can use to supercharge your cold email subject lines is to simply keep them short… no, really: that’s it. Sometimes less is more, and often this is the case when it comes to subject lines for emails.

An email subject line — warm or cold — that’s too long will fail to catch your intended target’s attention. This is primarily because of 2 reasons:

  • Eles geralmente são cortados após um determinado comprimento de caractere
  • They’re long winded and unfocused

On the other hand, shorter subject lines are specific, focused on a particular point or intended goal. They also never get cut off, which is a huge plus. 👌

So, how short exactly, is ideal? After all, it’s a rather vague term: what’s too long, too short, and just right? Well, there’s not an exact number; all subject titles are different: they’re promoting a unique email about a specific topic.

Too long is anything that gets cut off. What’s the point if they can’t see it? Too short is one that doesn’t get the message off you intended. Why even send the email if you’re not effectively telling them what it’s about?

For what it’s worth, there was a study done on email subject line length and open rates. These were the results:

  • 0-5 palavras = taxa de abertura do 16%
  • 6-10 palavras = taxa de abertura de 21%
  • 11-15 palavras = taxa de abertura de 14%
  • 16-20 palavras = taxa de abertura de 12%
  • 21-25 palavras = taxa de abertura de 9%

6-10 words length is the winner; I wouldn’t read too much into it, though. As stated before: each email is unique and requires a unique subject line. 0-15 words length will cover just about everything, but make sure to see if the subject line cuts off. Send it to yourself to check this out.

OBSERVAÇÃO: Also consider that the character length, not just the word length, is important. This is what determines the visual length of a subject line in an inbox, and if it gets cut off. Screen size and browser zoom can influence this. 🔍

If done correctly, here’s how it could look:

If done incorrectly, here’s how it could look:

3. Use a urgência em suas linhas de assunto de e-mail

Another strategy you can use to improve your cold email subject lines is to add some urgency. This is when you add something like ‘limited supplies,’ or ‘while stocks last.’

What this does is tap into a psychological phenomenon known as FOMO: the fear of missing out. People don’t like it when they let an opportunity pass them by; nobody wants to be the odd one out. In fact, according to research, nearly 70% of millennials state they experience FOMO. 😧

By putting some urgency in your cold email subject lines, you’re forcing them into action. Incentivizing them to click and open. The research backs this up: a report found urgency-laced subject lines could increase email open rate by 22%.

However, make sure you don’t go overboard. If too many of your emails use urgency, it kind of defeats itself. Think of urgency as a curveball you can throw now and again to catch them off guard. For cold emailing, though, you probably won’t have this problem.

Aqui estão alguns exemplos reais de linhas de assunto que usam o poder da urgência:

4. Use a prova social nas linhas de assunto de seu e-mail

Adicionar prova social às linhas de assunto de seus e-mails frios é outro truque psicológico que você pode usar. Assim como a tática da urgência, a prova social faz jogos mentais com seus alvos pretendidos. Isso ocorre quando você menciona algo que valida socialmente sua marca.

Os exemplos incluem:

  • Referência a quantos clientes você tem
  • Referência a depoimentos
  • Referência a estudos de caso
  • Referência a endossos de celebridades/autoridades/credibilidade

It works because people are influenced by what others do, say, and think. We naturally try to uncover whether something is credible or not: social proof helps us do so. When your cold email target sees your subject line mentioning your massive customer base, they’re impressed. 😲

Aqui está um exemplo real: este foi um e-mail promovendo um estudo de caso em vídeo.

Here’s another one: an email promoting a free guide from an SEO authority figure.

Here’s an email about another case study.

And lastly, here’s an email from Adam Enfroy that uses both urgency and social proof for his course on how to start a blog.


The subject line of an email, cold or hot, can make or break it: whether it’s successful or not. It directly influences the open rate, click-through rate, and conversion as well.

Cold email outreach is not an easy endeavor. The number of emails sent that get opened is typically quite low. Most don’t even reach the inbox: they end up in the spam folder. Others land in the “Promotions” or “Other” folder. 📂

No entanto, com a linha de assunto correta, você pode aumentar significativamente suas chances. Considere a possibilidade de utilizar as informações e os exemplos de práticas recomendadas descritos neste artigo; esperamos que sejam úteis para você.

Got any questions? Don’t hesitate to leave us a comment or hit us up on the chat on our website.

Um pouco sobre Will:
Will Cannon é um experiente profissional de marketing por e-mail e fundou o UpLead, um software de geração de leads B2B. Ele sabe uma coisa (ou duas) sobre excelentes e-mails frios e adora compartilhar seu conhecimento.

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