5 Most Common Email Subject Line Mistakes to Avoid At All Costs

The 5 Most Common Subject Line Mistakes to Avoid

So you’ve just put your finishing touches on that latest blog post, new YouTube video that you know is going to really help all those people on your list, your audience, though upon checking your open rates on your email service provider account, you’re quietly devastated at your low open rates. It hurts doesn’t it!

Where are the best subject lines? In your inbox! What makes you click on an email to open it?

Advertising legend David Ogilvy once said: 

Five times as many people read the headline as read the body copy. When you have written your headline, you have spent eighty cents out of your dollar.

Like a headline for a blog post or news article, the subject line for your email needs to capture people’s attention and convince them to open your message. A subject line can make or break the performance of your email, so it’s important to spend extra time crafting one that’s memorable and effective.

Good subject lines get to the point, create a sense of urgency and are relevant to the subscriber, but it’s easy to make mistakes when writing them. Committing these subject line sins can drastically reduce your open rates, but avoiding them is easy if you know what to look for.

Here are five of the most common mistakes people make when writing email subject lines, as well as tips to improve them and boost your open rates.

1. Using ALL CAPS or too much punctuation(!!)

Imagine receiving an email with a subject line like this in your inbox: GET 70% OFF YOUR NEXT PURCHASE RIGHT NOW!!!!!!!!!!!!!!!!!!!

Chances are you would take one of three actions: ignore it, delete it, or mark it as spam.


It can come across as though you are yelling, which can have a negative impact on your email performance. So you should use capitalisation and punctuation cautiously. 

Occasionally adding phrases like “Free” or “Act Now” have been shown to improve open rates, but I recommend using them sparingly to avoid diluting their impact. 

On a similar note, be sure to avoid using too much punctuation. You have limited real estate for your subject line, and multiple exclamation marks can come across as spammy. Special characters such as * % & # and ^,  have been known to trigger spam filters, so be sure to use them sparingly as well.

Now that we’ve gone over the punctuation mistakes to avoid in your subject line, you may be wondering which characters leads to more open rates.

The answer? Question marks, exclamation points and periods. 

Subject lines with exclamation points can expect an open rate that’s one to 20 percent higher than average – just as long as you don’t use them in every message.

While this can vary depending on your industry, your audience, and the content of your messages, I recommend testing multiple subject lines to see which forms of punctuation your subscribers are more likely to respond to.

By using simple language, asking a question, and using proper punctuation in her subject line, you’re able to pique the reader’s interest and entice them to read your message.

Exclamation points, periods, and question marks are all part of a healthy email marketing strategy, so don’t be afraid to mix up the punctuation you use in your subject lines.

2. Using Spammy Words

Adding certain trigger words to your subject line can activate a recipient’s spam filter, even if the message you’re sending is legitimate.

To prevent this from happening, avoid symbols like “$$$,” “100% free,” “cash off,” “cheap,” “weight loss,” and “serious cash”. Even if your email makes it into the inbox, it can come across as spammy to your subscribers.

To ensure your readers take your emails seriously, choose the language of your subject line carefully by avoiding some of the trigger words and symbols listed above.

Finding the right verbiage for your subject line can be tough, especially with the sophisticated spam filters out today. HubSpot put together an exhaustive list of email trigger words to avoid when composing your subject line, so reference it before sending your next message.

While there are plenty of recommendations for words to avoid in subject lines, there’s no hard and fast rule for ones to include; what works for one industry may not work for another. Be sure to try different variations of words to see what resonates best.

I also recommend focusing on specific words that tie back to the content in your email.

The subject line tells you exactly what you’ll get by opening up the email. And by focusing on that, it eliminates the risk of including words that might appear spammy.

3. Making It Too Long

Consider the environment in which your subscribers are reading your emails. Chances are, they’re on-the-go or quickly scanning their inboxes between work meetings.

Since you have only seconds to capture their attention, you want to make sure your subject lines aren’t wordy or redundant.

Long subject lines look spammy and get lost in cluttered inboxes, especially if readers are using mobile devices.

One favorite rule of thumb is  to keep subject lines no longer than 50 characters. To do so, aim to get your message across as quickly as possible and cut any unnecessary terms or phrases.

As important as it is to get your message across quickly and clearly, make sure it expresses a complete thought and offers value to the reader – you don’t want to write a subject line that’s too short, either. Avoid one-word subject lines and strive to be helpful and relevant to your subscriber.

Try building a message around a numbered list and including the word “secrets,” As a result, this subject line is easily readable and irresistibly clickable!

4. Writing misleading content

Let’s say you send an email with the following subject: Get an exclusive 50% discount on our entire inventory!

But when the reader opens the email, it’s a pitch to sign up for a webinar or free online class.

Not only is this tactic dishonest, it also tends to backfire. No one likes to be deceived, especially when they receive an email that promises one thing and delivers another. You might get people to open your email initially, but this alienates subscribers and can hurt your open rates and spam rates in the long run.

If your subscribers lose trust in your emails, they’re more inclined to ignore future emails and mark you as spam.

To build and maintain trust between you and your subscriber, make sure to align the content of your email and your subject line.

Also avoid subject lines that include RE: or FW:

These tend to trick the reader into thinking the email was part of another conversation, which doesn’t leave a positive feeling with subscribers.

Not including this text also gives you more room to work with in your subject line, which can be used to convey helpful and relevant information instead.

5. Including spelling or grammatical errors

Subject lines (or any other content in your email) with typos, misspelled words, and misplaced punctuation look unprofessional and can hurt your open rates.

Emails are an opportunity to establish your brand as a helpful source of information. Subject lines with spelling or syntax errors make a bad first impression, and undermine your ability to establish trust with your subscribers.

To optimise your email open rates, be sure to review your emails for grammar and spelling prior to hitting send. No one will take the time to read your email if the subject line is loaded with grammar mistakes, but basic copy editing can prevent these errors from slipping through the cracks.

Crafting subject lines that sweep subscribers off their feet…

The subject line is one of email’s most important components, so it’s important to get it right before you send your emails. And by avoiding the mistakes above, you’ll be well on your way towards improving your email engagement.

I really hope this helped. Hey, have I missed anything here though? Drop me a note in the comments section below and let me know your thoughts. 

Do you have any subject line best practices that weren’t listed in this post? I’d love to hear about it in the comments below!


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About Phil

Phil Adair is the host of one of the most downloaded online marketing podcasts on the internet. (Go here to subscribe and listen to The Online Marketing Strategies Show.)

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10 Reasons Your Website Copy Might Need Some Love

Made any improvements lately? – your headlines and call-to-actions in particular?

 Making your text much more engaging and captivating is actually one of the quickest and highest-impact ways to improve your website conversions and sales.


It doesn’t matter how good your website looks if your text doesn’t sizzle and captivate – your visitors won’t be excited to learn more and will bounce often – meaning many lost sales for you!


You don’t have to have a degree in marketing to write more captivating text either – Here are some expert tips to help you quickly become a copywriting pro, and convert many more of your visitors into sales.


1: Captivate visitors by mentioning their needs and pain points


Often the best way to improve the effectiveness of your text is to think in your visitor’s shoes and prominently mention words on key entry pages that relate to (and solves) their main needs, problems or frustrations.


Try asking intriguing questions in your text that your visitors can relate to (particularly in your headlines) and then mention why your offering is the best solution for them. Researching more about your main types of visitors and getting feedback from them is essential to do this.

2: Focus on benefits and results of your product/service – not just features


Your visitors of course need to know your product/service features, but many websites forgot to also translate them into benefits and potential results – which is what your visitors really ultimately care about.


Therefore its essential you prominently mention these on your product/services pages – for example, if you are selling services, you should mention the benefits (saving time, effort etc) and impact on revenue for your clients – not just the service features.

3: Use proven highly-engaging powerful words far more often


Give your website text a makeover by using time-tested marketing power words. How many of these great examples below are you using on your website? Go ahead and check right now, particularly for your key entry pages, and start introducing more:


Discover, Secret, Results, Imagine, Guaranteed, Instantly, Powerful, Easy, Simple, Exclusive…

 4: Do the ‘we we’ test to make your text more visitor-focused


To engage many more visitors, focus your words on their viewpoint, not on you or your business – so avoid using ‘we, I or us’ and your company name too often. Instead, use much more visitor-orientated and friendly words like ‘you’ and ‘yours’.


To help improve this, you should to the ‘we we’ test to check how many times you use each type of business or visitor word on your key pages. Make sure you use higher amounts of visitor-focused words – doing that will instantly upgrade the engagement of your text!

5: Write magnetic headlines to hook your visitors


Your headlines can make or break whether your visitors stay on your website or bounces prematurely.


Try using several styles to see which converts best, including benefit driven ones, social proof or testimonial focused ones, or pain point related questions. This tool helps you analyze how good your headlines are.


“On the average, five times as many people read the headline as read the body copy. When you have written your headline, you have spent eighty cents out of your dollar” David Ogilvy


Don’t forget to also test your headline size to make it stand out more, and the number of words used (short and sweet is better – ideally under 10 words). Here’s a great headline combining many best practices:

6: Know which boring and dull words to avoid like the plague

Some words are just a waste of space and opportunity on your web pages, and should be replaced with much better, more engaging words.


Here are some of the most conversion-killing words I still see way too often that you should avoid:

  • Submit (use a much more engaging word that implies the benefit of clicking)
  • Click here (pointless self-referential words – wasted opportunity to write a better call-to-action)
  • Cheap (makes your service/offering sound low quality – use ‘low cost’ or ‘affordable’ instead) 
  • Utilise, leverage, mission statement and other corporate words (too dull)


Edit ruthlessly

7: Ruthlessly cut your text and make it concise

To increase the chances of visitors reading your text and seeing your key points, you need to start really cutting down the amount of words you use.

Shorten your paragraphs and sentences, cut out fluff words, unnecessary extra detail words, and don’t ramble – be direct. If the words don’t help explain anything, or don’t add any real value to the sentence, then get rid of them.

8: Focus on improving your call-to-action button wording

The wording of your call-to-actions are critical – it’s essential you persuade more visitors to click on your buttons and key links. Always avoid using generic words like ‘learn more’, ‘submit’ or ‘subscribe’ – use much more compelling text instead.

Benefit and power related words will work well, as will using action-driven words, which leads us nicely into the next tip.

9: Inspire action – use words to get your visitors to act quickly


Realise that your visitors are often in a rush and don’t have much time, so get them to act quickly on your website offerings.


Action words are particularly important for using on your call-to-action buttons and links. Here are some good examples of action words to help you come up with ideas to test:


Now, Today, Get started, Fast, Quickly, Discover, Create, Instantly, Try, Learn, In Seconds.

10: Use sub-headers to make your text much easier to scan

Remember that visitors don’t read online the same way they do books or magazines – instead they scan text and will only read more if something catches their eye. Making use of many descriptive sub headers will make your text much easier to scan – they also help to break to categorise and break up long blocks of text.


I really hope this helped. Hey, have I missed anything here though? Drop me a note in the comments section below and let me know your thoughts. 

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Phil Adair

Hot Clicks Pay-Per-Click Online Marketing

Suite 12, 5th Floor, Dymocks Building

428 George Street, Sydney 2000, NSW, Australia  

W: hotclicks.com.au

I’m a huge fan of connecting on social media. If you’re on these social networks, then let’s follow each other: 








About Phil Adair

Phil Adair is the host of one of the most downloaded online marketing podcasts on the internet (Go here to subscribe and listen to The Online Marketing Strategies Show.)

Read his inspiring bio now.

Feel free to send Phil a message here >>