No matter how sexy your email content is if your subject line sucks or makes you end up in SPAM you’re busted. Fortunately there’s many information available on the web about how to write killer subject lines and which words to use to make your emails noticed.

email subject line words

Adestra – one of the biggest ESP in the UK – analyzed over 2.2 Billion emails to figure out which words work best. Here are the top 8 keywords they identified:

  • Free delivery
  • Available
  • New
  • Alert
  • News
  • Update
  • Summer
  • Weekend

We have to add that besides subject lines the frequency of email sending also had a huge impact on open rates. Daily (+27.8%) and weekly (+27.1%) newsletters seem to work the best (depending on industry) while monthly newsletters were opened 26.6% less.

Unfortunately there’s no information about how the time of the day influenced open rates. The old “rule” seems to be mid-week + mid-day sending (1-3 pm) but don’t take it granted, since for example another study showed that late night (8 pm to 12 pm) sending will bring you the highest open and click rates. There’s no golden rule, so you simply have to invest your time to figure out what works best for you.

Alchemy Worx – a global email marketing agency – conducted two different email subject line studies which looked at over 45 Billion emails in total (21 Billion + 24.6 Billion). The most successful words seem to be the following:

  • Upgrade
  • Just
  • Content
  • Go
  • Wonderful
  • Jokes
  • Promotional
  • Congratulations
  • Revision
  • Forecast
  • Snapshot
  • Token
  • Voluntary

“Magic” words + …

No matter how many emails were analyzed to get these results, don’t take these words too serious. Get inspiration from what you saw above, and craft your subject lines likewise. After you come up with 2 or 3 different subject line versions, always test them with people around you, with your colleagues, friends and preferably do A/B tests as well.

Don’t forget to personalize

75% of people love if they receive personalized messages. This is the primary reason why personalization increases click through rates with 14% and conversion rates with 10%. Basic personalization is quite easy, since you only need to include the name of the person, but advanced personalization can become quite complicated and you may even need to switch to a marketing automation tool instead of a classic ESP.

Do it your own way!

What works for one company may not work for another, and of course if you send out tons of email, you still need to renew your subject lines from time to time, since people will easily get bored if they receive the same stuff. No matter if it contains a HUGE discount or the magic word FREE.

Did we miss your favorite word? Feel free to add it to the comments section. We would love to get more inspiration from you!

Roland Pokornyik

Roland Pokornyik

CEO / Co-founder @ &

  • Email Marketing and Mobile Optimization Email Marketing and Mobile Optimization

    Read more
  • 16 Command Examples to Send Email From The Linux Command Line 16 Command Examples to Send Email From The Linux Command Line

    In this post you'll learn how to send emails from the Linux command line. I'll show the most often used commands, SMTP configuration and terminal options.

    Read more
  • How to Create Responsive Email Designs with React Native How to Create Responsive Email Designs with React Native

    Responsive email coding is complex. Are you native in React Native? Abstract away email HTML & CSS into components with react-html-email or mjml frameworks.

    Read more edmdesigner @ copyright - EDMdesigner