Niraj Ranjan
August 21, 2016

8 Do’s and Don’ts of Cold Email Subject Lines

emai subject lines

69% of email recipients report email as Spam based solely on the subject line. The impact of a bad email subject line is far worse than you would think and often, it is indeed hard to identify which subject line will be perceived as bad by the reader. It depends on many factors, including something as frivolous as the reader’s mood.

Having said that, there are some general do’s and don’ts which work most of the time and are generally accepted as effective while sending cold emails.

The moment a person sees a mail from a new sender, they will look at the subject line to decide if they should open, delete, or worse, mark as spam. This makes your subject line a powerful decision point and hence, be scrupulous, smart and creative when crafting them.

Here are some Do’s and Don’t’s for email subject lines:


1. Craft timely and relevant subject lines

On a rainy day, if you send out an email with a subject line ‘Rains killing your business? Let’s do something about it’ chances are you will catch people’s attention.

If the subject line addresses hot topics on the news or a recent event everyone is raving about, it will generate more interest and awaken their curiosity. Once you have their interest piqued, they will be relatively more open to what you have to say.

2. Make it succinct – the shorter the better


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Emails with subject lines containing 30 or fewer characters have the best open rates.

Remember that the longer you go, the lesser the probability of them opening your email becomes.

Shorter subject lines are easier to read and there is also lower risk of them getting cut in the midway. In a regular inbox you can see about 60 characters in a subject line and for mobiles, it’s even less, say about 25-30 characters.

3. Make it action-oriented


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By including action words in the subject line, you are straight away telling your reader what you are expecting from them and what the purpose of the email is.

Make sure to write the subject in an active voice. Action-inducing words certainly catch readers’ attention and may even push them to act.

For example, subject lines like, ‘Watch my latest video on productivity’, ‘Download an eBook on Google apps’ etc. convey the message succinctly and urge the readers to take action.

Sometimes, action-oriented subject lines can be in the form of questions tapping into something the reader is already interested in. For example, if you are sending an email to a writer, a subject line like ‘What would your ideal writing space look like?’ will catch their attention.

4. Identify the sender

The ‘unknown sender’ title will inspire doubt and suspicion in the recipient. The from line is as important as the content of the subject line.

Say you send an email with the subject line ‘Please donate to save a person from malnutrition’ from an ‘unknown sender’. What do you think the recipient will do? They will categorize you as a scammer and delete the email instantly.

Make sure the reader can recognize the sender or at least understand who it is from. Don’t use email ids like ‘’. I wouldn’t open a mail from this guy, would you? In essence, put yourself in the reader’s shoes before sending anything. The chances are high that what turns you off, also turns them off.

5. Use preview text to boost the effect of your subject line


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The line of text that appears right next to your subject line is the preview text. It gives a space for you summarize what the email is about.

The preview text should complement your subject line – should basically be an explanation/reinforcement of the subject.

Giving your recipients a peek at what’s about to come will drastically improve your open rates.

Here is an example of a subject line and preview line that complement each other:

‘Are you a tech lover?’ – subscribe to get latest tech news, product reviews and trend reports


1. Don’t use spammy words and desperate tactics


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There are some words which email providers hate and which will send your email straight to spam. For example,

  • Free
  • Cash
  • Offers
  • Credit
  • Limited time

Email subject lines such as ‘Need cash urgently? Contact us’ will trigger the spam filters. In addition to words, using special characters like too many exclamations or cute symbols such as ‘Hurry!!!!!’ ‘@321’ etc can attract spam attention.

Even if it doesn’t get filtered through spam filters, people will still not open these emails for the fear of being scammed or wasting their time on useless internet cons.

2. Never send generic subject lines

In this data-driven age, sending emails with generic subject lines is only demonstrative of how little you care about the recipient and how lazy you are.

There’s heaps of data available on people based on demographics, age, sex etc. and there are tools which can help you get to know them. Use this to your advantage. For example, you can reference locations to personalize email subject lines for example, ‘Dear New York residents, we have some good news for you’ etc.

When the recipient’s inbox is overflowing with all sorts of emails, why will he pick to open a sorry little generic and vague email?!

3. Don’t make overly-exaggerated or fake promises


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‘Never get sick again’

‘Do this course and you will win at everything in life’ etc.

Subject lines such as these will make the customers question your credibility and pass your email off as another self-promotion tactic.

Even if you get a reader to open the email, if you fail to deliver on the promise you made in the subject lines, you have ruptured your prospects with them and they will probably mark you as spam for future emails.

Authenticity is the key. In the subject line, say exactly what you want to do – not less, not more.

Final thoughts

It is relatively harder to get a cold email opened. Hence, the need to strategically craft your subject line gets amplified since it is the pivot point at which the customer can choose to delete or open. So before sending out cold emails, read a lot of emails etiquette and subject line best practices in order to write click-worthy subject lines.


Lead/Featured image: Copyright: ‘‘ / 123RF Stock Photo

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Niraj is the founder of Hiver, an app that turns Gmail into a powerful customer support and collaboration tool.