Experts say that not including a subject line is one of the biggest mistakes you can make. The subject line often determines whether an email gets opened or not and how the reader reacts. An email with a blank subject line will likely get deleted, lost, or immediately irritate the recipient, who is forced to open the email to figure out what it's about.

And that’s why almost all articles about subject line optimization tips or articles about how to write a subject line start with: ”write the subject line first” and that’s also why we at FastDeliver give the user ability to write the subject line and preview text before even starting to write the email
N.B: Preview text is the text shown after the subject line in emails list to the recipients

So, what decides the quality of the subject line? Simply, these tactics

  1.      Benefit
  2.      Curiosity
  3.      FOMO (fear of missing out)
  4.      Power words
  5.      Exclusivity
  6.      Lowered risk

Apply these simple tactics in writing your subject line and your open rates will be boosted.

Let’s break them to know more about every tactic

  • Benefit

If your recipients see there will be any benefit for them, they will immediately open your email, there arises also the importance of building an accurate email list not just purchasing it, so you can detect what interests them

Examples of benefit words:

  • Drive traffic
  • Boost sales
  • Improve at work
  • profit

  • Curiosity

Humans tend to reveal any unknown – we don’t like having gaps in our knowledge. You can leverage this desire for revealing the unknown by leaving your subject line open-ended so subscribers will be curious and leaving the subscribers no choice other than opening you email if they are interested and aroused by your mystery topic

You can make recipients curious by asking questions, promising something interesting, or simply saying something that sounds strange or unusual. A good way to create curiosity is to use these formulas:
- “[Number of ways] + [Pain points your product solves] that you should avoid”

- “[Number] + [Tips/Strategies/Hacks] to [Achieve your goal]”

Examples of curiosity words:

  • Mystery
  • Unknown habits
  • How I reached _________
  • A surprise
  • Gift


  • Fear of missing out (FOMO)

A Purely psychological tactic that’s really very hard to resist is the FOMO, FOMO can be used in the subject line to drive feeling like scarcity and urgency

Examples of FOMO words:

  • Expiring offers
  • Missing out
  • One day only
  • Ends by midnight
  • limited


  • Power words

If you really understand your recipient’s needs, you should know their biggest pain points. Use those pain points, convert them to power words that solve their problem and reinforces their business/personal position or situation to get subscribers to open your emails.

Examples of Power words:

  • Premier
  • Complete
  • Bonus
  • Profit
  • Growth hacks
  • promote


  • Exclusivity

The psychology of exclusivity is a powerful thing. When people feel like they're on the inside, it gives them a sense of belonging that could build loyalty and compel them to convert better on your emails.
The right phrasing can make your recipients feel special -- and the effect can be magical.

Examples of Exclusivity words:

  • VIP Only
  • Exclusive
  • before anybody else
  • Competitive
  • Only to subscribers
  • Insiders requests
  • Private Invitation


  • Lowered Risk

No one wants to risk dealing with you, especially if you are cold mailing them to sell a product or service. They will want to lower the risk if trying something new, they wouldn’t risk buying an item if it’s not tested or not guaranteed. So you must make sure to lower this risk for them if it’s cold mailing they might not believe you at the beginning but this will help to lower the risk

Examples of Lowered risk words:

  • Certified
  • Refundable
  • Free trial
  • Guaranteed
  • Money-back guarantee
  • Tested
  • Secure
  • reliable


So, the trick is that you don’t just use one of them, everyone can do this, but rather use a combination of two or the three or even more of them and the more you apply the more quality is your subject line.

Now let’s take some sample subject lines and analyze them

How I got 7,068 Subscribers in 57 days
Tactic: Benefit, Power, Curiosity

Grow your business with these simple tactics
Tactic: Benefit, Curiosity

[Weekend Only] 30% discount on all gifts
Tactic: Benefit, Power, FOMO

Be the first to apply these new tactics to increase your YouTube channel views
Tactic: Benefit, Power, Curiosity, Exclusivity

Purchase now to get 30 days money-back guarantee
Tactic: Benefit, FOMO, lowered risk

Get offer now before it’s gone
Tactic: FOMO, Exclusivity

Amazing added value to your business
Tactic: Benefit, Curiosity

Guaranteed 674+ leads for you
Tactic: Benefit, Lowered Risk

Double your video quality using this simple trick
Tactic: Benefit, Curiosity

There’s a lot of sample email subject lines to show and analyze, they are all over the internet, but if you focus a little bit, you will find that the best subject lines with most open rates are following this strategy.

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