How to write email subject lines: What to do and what not to do

Subject LinesThe number of emails I receive daily can range from 10-50, from daily deals to newsletters. Yet, I always have an internal debate with myself as to whether I open or delete these emails, and I think to myself…

  • Does the email entice me?
  • Will the email offer me some added value?

But, what makes me decide to do so for each email?.. Simple – Subject lines!

It is email marketers’ jobs to provide readers with an enticing insight into an email’s content, whilst giving the reader an impression as to what the email is about. The subject line acts as a ‘window’ to the email and is arguably the single most important part, to determine whether the e-mail is to, or not to be opened, which is used by 100% of businesses (Ellis-Chadwick and Doherty, 2012) – with the need to have a consistent link between the subject line and email content.

Subject lines in the e-mail are the first point of contact for readers, and acts as a trigger to encourage the message recipient to open the email. There are 2 main components in the subject line: e-mail sender and e-mail content (Ellis-Chadwick and Doherty, 2012).


But first – how to write an email subject line?..
16 tips to writing an email subject line (Goudreau, 2015):

  1. Always write a subject line.
  2. Write the subject line first.
  3. Keep it short.
  4. Place the most important words at the beginning.
  5. Eliminate filler words.
  6. Be clear and specific about the topic of the email.
  7. Keep it simple and focused.
  8. Use logical keywords for search and filtering.
  9. Indicate if you need a response.
  10. Set a deadline in the subject line.
  11. If someone referred you, be sure to use their name.
  12. Highlight the value you have to offer.
  13. Personalize it with the recipient’s name or company name.
  14. Create urgency by limiting the timeframe.
  15. Don’t start a sentence that you finish in the email’s body.
  16. Make sure you reread the subject line.


Below also indicates what you should and shouldn’t do/include in your subject lines.

What to do…
Here are 10 great examples from Hubspot (2015) to document the ways in which email subject lines can attract attention.

 10 Examples of subject lines and why they’re good

Company E-Mail subject line Why the examples are good
1.) Warby Parker “Uh-oh, your prescription is expiring” Timing, correct tone and informal
2.) Groupon “Best of Groupon: The Deals That Make Us Proud (Unlike Our Nephew, Steve)” Humour (unexpected)
3.) Rent the Runway “Happy Birthday Lindsay – Surprise Inside!” Personalisation, offer eludes to an incentive (added value)
4.) Barack Obama “Hey” Informal (over familiar language) offers intruige, unlikely subject line and sender pairing
5.) Manicube “*Don’t Open This Email*” Curiosity
6.) Refinery29 “The broke girl’s guide to a luxury vacation” Self-identification
7.) Zillow “What Can You Afford?” Playing off physical emotions
8.) UncommonGoods “As You Wish” Thinking about what makes people tick
9.) DocuSign “What are our customers saying?” Relevant facts for customers
10.) Eater Boston “Where to Drink Beer Right Now” Timing (sent at 6:45pm) – engagement


These subject lines appeal to audiences through the use of questions to directly engage with readers, offering them a way to stop and think about what is being asked, a conversational and informal stance, offering added value, personalisation and humour. Hubspot (2015) further suggest that principles like urgency, scarcity, and social proof are all also great ways to increase conversion rates.

Ellis-Chadwick and Doherty (2012) found that more than 56% of emails sent by businesses, offered an incentive in the subject line, predominately based upon a discount or saving (28% of the emails) and occasion or seasonal promotions (10%). Furthering from this, they also found that 44% of marketing emails offered no incentive in the subject line, which were most commonly newsletters, product information, or ‘teaser’ messages about forthcoming new products.


What not to do…
However, it is very easy to get subject lines wrong.

Words to be avoided within subject lines

Number Words / Examples Justification
1 Free Triggers spam filters, but ‘free delivery’ has been shown to drive response uplifts
2 Help, % off, reminder Regularly discarded
3 Save today, don’t miss Does not entice readers to open emails
4 Holiday sales event Too ‘salesy’, instead use promotion or newsletter
5 FWD: and RE: Deceptively enticing customers to think communication has already been established
6 NEW OFFER Writing in capitals, is too harsh and direct as an approach
7 Hello Chris… (sent to Tom) Personalisation data has to be correct, and doesn’t always result in open-rates
8 🙂 !!! … [ ] < > <3 Unnecessary use of punctuation or emoticons
Source: Compiled by author, information from Ratcliff, C (2014)


The purpose of the table is to demonstrate that customers value straightforwardness and that subject lines must be relevant and enticing, and should be used 100% of the time according to Ellis-Chadwick and Doherty (2012).

I received an email the other day, which included an emoticon in the subject line, which can be seen below. Immediately I didn’t open the email as I could tell it was a spam email and one which I wouldn’t be interested in, especially due to the unnecessary heart included, which is a ‘no-no’ according to Ratcliff (2014). The email also tried to entice me in by having the senders name as a first name, trying to suggest that I have had some prior correspondence with the sender, lulling me into a false sense of security, in an attempt at personalisation. This was a clever move by the sender, but was an immoral way of sending emails.

email picture cropped

Subject lines are critical for engagement and grabbing attention of readers (Ellis-Chadwick and Doherty, 2012). However, subject lines need to be tested as different triggers or language may work for different audiences, as well as for different purposes.

Ellis-Chadwick and Doherty (2012) suggest that using variant testing should be used to determine effective subject lines, by understanding what will engage the customer most, via looking at the greatest open rates.

Common misconceptions about email marketing from Alchemy Worx (2013) state that key words have little or no effect on the subject line ending up in the junk folder according to 54bn sent emails, and shorter email subject lines do not give better results under 60 characters.

Ellis-Chadwick and Doherty (2012) summarise the importance of subject line… ‘Subject lines MUST grab the initial attention of the customer and prompt him or her to open the email; otherwise, there is no opportunity for sustained attention; the message can be deleted and never seen again, unlike print media messages, which can be returned to later’.


Alchemy Worx (2013) Debunking the 7 myths of email marketing – Infographic [Online] <–-infographic> [accessed 1 April 2015]

Ellis-Chadwick, F., & Doherty, N. F. (2012) Web advertising: The role of e-mail marketing. Journal of Business Research, Vol. 65 (Issue 6), p843-848

Goudreau, J. (2015) 17 tips for writing an excellent email subject line. Business Insider UK [Online] <> [accessed 1 April 2015]

Ratcliff, C (2014) 45 words to avoid in your email marketing subject lines. Consultancy [Online] <> [accessed 1 April 2015]

Soskey, G (2015) 18 of the best email subject lines you’ve ever read. Hubspot. [Online] <> [accessed 1 April 2015]

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