Write a great subject line for optimal open rates

Apr 21
5 min read
The subject line is by far the most influential element when opening an email. Here is how you can improve your results.
Be brillant in neon. Subject line

Wherever you receive email, they all present a list to the user. It's up to him to decide if he will continue reading your message, or not.

When writing content, you should always ask yourself these two questions:

  1. Is it enticing enough? Will I optimize my open rate by writing it like this?
  2. Does it hurt my deliverability? In length & terms used, am I in the rules?

Get to the point

This is harder than it looks. The secret is being clear and concise. At the same time.


Through your subject, you must make clear what the user will discover when opening it. You can aim for curiosity and a dose of mystery. But don't overdo your subject line with an effect that is ruined by the email itself. This is even more true for promotional emails. Otherwise you risk unsubscribing or worse.


You will have to remain clear, short and concise at the same time!
We advise you to try to aim for 20-30 characters.


Don't go into too much technical jargon. This goes back to the previous idea of making your topic short, but your topic must be catchy. In other words, it should be the one that stands out from the mass of other emails in the inbox. And for that:

  • Use only powerful words, avoid being bland and rely on more emotional terms,
  • Use action-oriented verbs,
  • Focus on urgency,
  • Do not use a succession of short keywords that do not add value

Be careful with some spam keywords

The following keywords are not forbidden. But they do constitute an alert for anti-spam filters which have a very critical eye. Avoid their use as much as possible, as it risks your deliverability:

  • terms related to freebies, discounts,
  • anything commercial, purchases,
  • monitored themes such as "money at home", clairvoyance, sexuality, health
  • overbidding on trust: "this is not spam", "you have been selected", etc.
  • excessive use of capital letters and punctuation is to be avoided.

In short, most of the time it's common sense. Don't write a subject line the way a spammer might. If you think your topic uses jargon considered spammy, for ex. dating or finance, take a more creative approach.

Optimize your title

Use analytics, personalization and A/B testing; run tests and see which messages work best. Cakemail provides you with clear reports and a simple interface. This will help you to watch and iterate new headlines.

Related content

  • To fully optimize your open rate, also improve your preheader,
  • The rules about keywords are also true in the email body. But there are other good practices are to take into account,
  • Before writing anything, you should have a good template. The technical setup is very important to optimize your deliverability and engagement.

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