Home Affiliate Marketing Blog 17 Email Subject Line Best Practices

17 Email Subject Line Best Practices to Follow

17 Email Subject Line Best Practices to Follow

If you’re a regular sender of emails, you know that your subject line is crucial.

The right subject line will get more of your emails opened and read.

More emails read will lead to more conversions for you. An uninteresting subject line will leave your email unopened — or worse, send it straight to the trash — and what good is that to you?

The best subject lines are short and descriptive enough for your reader to WANT to open the email and see what it says. Don’t try too hard to stand out in the inbox; instead, work on simplicity. That's what gets emails opened.

Need some more help writing the perfect subject line for your emails? Here are 17 of the best tips on crafting a good subject line for email marketing.

1. Keep It Short

The length of your subject lines is a very important factor. Not only are shorter subject lines easier to read, they’re also less at risk of being cut off midway by the email provider.

A regular inbox usually shows only about 60 characters of the subject but if you're on a moble, it's even shorter with only 25-30 characters visible. 

Best practice? Keep your subject lines limited to 45 — 50 characters in length. Just get straight to the point. 


This subject line is way too long and gets cut off in my inbox. Not good. 

2. Put Important Information First

When writing your subject line, be sure to place your most important and compelling bits of information at the beginning of the subject line.

Most languages are read left to right (English is obviously no exception), so when you put the juicy bits at the beginning of your subject line, you’re grabbing your reader’s attention right away.

Also, if your subject line does get cut off (especially on mobile), your subscribers will at least see the most important information first.

The subject line above is not only short — it puts the most important information first: Traffic. 

3. Avoid These Words ...

You probably already know this, but when you use certain words in a subject line, your email is doomed to end up in the spam box.

Words email providers hate:

  • Free
  • Credit
  • Cash
  • Offer
  • Act now
  • Limited time

Additionally, a MailChimp study of over 200 million emails also found that seemingly innocuous words such as Help, Reminder and Percent Off also negatively affected open rates. HubSpot has an excellent list of email spam trigger words that I recommend you check out. Interesting stuff!

The following are some emails from my spam folder that use the trigger words in their subject lines.

spam email subject lines

4. ... and Other Spammy Tactics

Email providers hate certain words, but that’s not all that will earn your emails a one-way ticket to the spam box. To save your emails from dying a spammy death, some things you should probably avoid doing are:

  • Overdoing the exclamation marks!!!!!!!!!!!!!
  • Using @#!**^$!@ expletives
  • g3tt1n9 2 Cr8ive with numbers and characters

Just do the right thing and be ethical about your email marketing practices and you won't have any problems. 

5. Make It Straightforward

Don’t try to be cute — leave the quirk behind and forget about the tease.

Make your subject lines as straightforward as they can get. When your reader receives an email, they should immediately know what to expect from it. Straightforward and to-the-point subject lines get more opens.

living social

The above email from LivingSocial is a great example of a straightforward subject line. I know exactly what to expect when I open this email.

6. Include a Call to Action

Action-oriented subject lines almost always work well. Your subject line should be written in the active voice in order to get your reader's attention. By including action words in your subject line, you’re telling the reader what you want them to do when they read the email.


  • Watch Beyoncé in concert
  • Download affiliate marketing whitepaper
  • Shop the '90s trend

rebecca tracey

This email from Rebecca Tracey has a great call to action, inviting her subscribers to get a product for a discounted price. 

7. Ask Questions

Continuing on from the call-to-action tip, readers also respond well to questions in subject lines. Think about what your audience needs or is interested in. A timely, relevant question will often get more opens. If your email content is answering an important question your audience has, consider using the question as your subject line.

freelancer email

This subject line gets my interest by asking a question about a topic I'm likely to be interested in.

amazon email

This subject line is also a great example of asking a question to get a job done. If I want to share my experience of the book with others, I will open the email and give out those stars. Job done for Amazon.

8. Identify Yourself

Don’t forget about the From line. This is just as important as your subject line. Again, keep it simple and use it to identify who you are to the reader.

Whatever name you use, make sure it’s one the reader can recognize immediately. Keep this consistent and try not to change it too often.

unknown sender

The above email is clearly spam, but what makes it worse is they don't even try to identify themselves. Why would I open an email that says "unknown sender," especially one that is asking me for a donation?

9. Be Urgent

An email subject line that clearly identifies the urgency of action is often a winner, too. Many email marketers like to add the word "Now" to their subject line to convey this urgency. Example: “Get your dream body. Download our 31-day programnow.”

Others will add a time/day factor. For example, this email about a webinar:


just shop

10. Localize

Most of us have a lot of data about our audience, including their location. Instead of personalizing emails with first names, how about using their locations instead? For example, “New Store Opening in Cleveland” is great because it's relevant when you send the offer to your readers in and near Cleveland.

On the other hand, “New Store Opening” is much too generic and doesn’t really pique any interest.

11. Be Clear About Value

What value are you bringing to your subscribers via your email?

You must make this very clear through your subject line, as this will convince your readers to open the email. Your subject line should immediately make it obvious to your subscribers how they will benefit from your email.

For example, a subject line that says "Increase your traffic by 30%" is way more valuable than "How to increase traffic."

For example, the emails below are from Affilorama and both subject lines immediately highlight how I am going to benefit by reading this email. One tells me about a workshop to learn how to make better profits while the other is going to teach me how to grow my social audience. From the subject of these emails, I definitely want to know what the content of these emails are.

affilorama email

12. Don't Make False Promises

Never, ever, ever try to trick your subscribers.

Don't make a promise in your subject line that has nothing to do with the content of your email. This is not only spammy, but you will lose your subscribers' trust.

Keep it simple and straightforward and don't attempt to get your readers to open an email that doesn't deliver on the promise. Keep it up and you'll almost assuredly end up in the dreaded spam folder.

13. Add Preview Text

The preview text is the line of text that appears in your inbox, alongside your subject line. 

It's worth spending some time composing preview text that complements your subject line, as it give your subscribers a sneak peek at the content of your email. A well-thought-out, strategically crafted line of preview text can have a huge effect on your open rates.


For example, this email from Dropbox uses the subject line to tell me that Dropbox has new features and the preview text reinforces the message by telling me how I can unlock these new features. I immediately want to find out more.

14. Leave Out the Filler Words

Don't bother with using words like "hello" or "thank you" in your subject line. These simply take up space in prime real estate.

Use your subject line to to convey your message as shortly and succinctly as possible. Save the greetings and other filler words for the body of your email.

15. Use Numbers

Numbers in email subject lines work just as well as they do for blog posts, so use them.

People love a numbered list or a number that tells them something is going to be easy (e.g. "4-step process" or "5-minute video").

mish rob

The use of "3" in the above subject line tells me it's a short, simple process to keep my inbox organized. I'm interested and definitely want to see how this is possible.

16. Keep It Timely & Relevant

If your subject line addresses something that has been in the news or references a recent event or even something that has gone viral, you are likely to generate more interest. A subject line that is more relevant or timely will make your audience open the email to see what you have to say.


“See what Grumpy Cat can teach you about business”

Snow day killing business? Take your store online”

Grumpy cat

People love a good Grumpy Cat meme, so you’re piquing interest with the reference. In the second example, you make a topical and timely reference to snow days and how they affect businesses. You then use it to sell your eCommerce business product. Business owners are worried and will want to open your email to see whether you really have a solution for them.

17. Keep Testing

The best way to determine if your subject line is a good one? Testing. Test a few different variations to see which one performs better. Constant testing will improve your open rates and make you a better email marketer.

For example, you could send the same email with two different subject lines to two groups of subscribers and see which one gets better results. 

So you’ve followed all the best practices and have the perfect subject line. Does this guarantee 100% of your emails will be opened? Absolutely not. However, it does guarantee that MORE of your emails will get opened.

Email marketing is subjective and at the end of the day, it depends on the actual person receiving your email. You can’t please all of the people all of the time. By following these best practices, you can please most of them, most of the time. If 85% of your email list is opening and reading your emails, I’d say you are pretty successful.

What do you think is the number-one practice to follow for email subject lines? What have you had success with? Do share I’d love to know what has worked for you and what hasn’t.

P.S. If you want to learn more about email and newsletter strategies, be sure to check out our free lessons on email marketing

12 Comments Add your comment
  • Reply Ugo Okonkwo • 2741 days ago

    Am pleased to say that I actually do 99.9% of these with my emails already - except time of day. Need to look into how I could use that :)

    Radhika Basuthakur2740 days ago

    Hi Ugo! That's great that you're following best practices. Experiment with subject lines that address timeliness to see what sort of results you get.

  • Reply David Hornbeck2741 days ago

    This is excellent information as always. I was unaware that the spam trigger list was soooo long. I will employ these best practices in the future.

    Radhika Basuthakur2740 days ago

    Thanks for your comment David. It sure is a long list isn't it? I think if you try to keep your subject lines to the point and informative rather than the over-the-top salesy, you won't have much trouble with the spam filters.

  • Reply Anoop Srivastava2741 days ago

    Radhika, I have just read one of the post https://www.affilorama.com/content-creation/email-subject-lines and find good one. I am using the All Capital Words in Subject and now understand why not getting the response. Thanks!!!

    Radhika Basuthakur2740 days ago

    Hi Anoop, glad that the article helped. All caps is definitely a no-no in internet communications. It's spammy and looks like you're shouting at the reader. No one likes to be shouted at ;)

  • Reply sham bennett2741 days ago

    Some really useful advice in this post Radhika. It just so happens, I'm currently writing a post myself 'The Email Marketer' for my Affiliate marketing site.
    I think alot of emails most people receive screams out 'Spam' and few of these are massively acted on. Mainly becuase alot of emails I've seen in recent years contain very few - if any of these 11 steps.
    Emails are subjective, and what appeals to one person, may not appeal to the other. A well prepared email never guarantees there'll all be read, but they are more likely to be opened by prospects.

    Radhika Basuthakur2740 days ago

    Very true Sham, there are no guarantees about what makes someone open an email but at least we can *try* our best to make the email sound as appealing as possible.

  • Reply Brian Reynolds2741 days ago

    Good an sound advice there.It's case of making the mail normal looking to encourage the recipient to open it to see what's inside,especially it it ends up in the Junk Box first..

    Radhika Basuthakur2740 days ago

    Thanks for your comment, Brian. Yes exactly - you want to convince the reader your email is worth opening.

  • Reply richa yadav • 2741 days ago

    Nice document for all basic important points related to email writing.

  • Reply Richard Brokenshire • 2741 days ago

    Thank you for the lesson in subject lines! I needed that for sure. What are the average open rates for marketers? And what kind of increase should I expect using these best practices?

    Radhika Basuthakur2740 days ago

    Hi Richard. Glad you found the article useful. Like I said in the article - emails can be very subjective and open rates can vary depending on the industry or demographics. I think on average, open rates for email can be between 30 - 60%. You would have to do your own testing to see what the open rates are for you and then see if they improve when you follow the best practices for writing subject lines.

  • Reply Richard Brokenshire2741 days ago

    Thank you for the lesson on subject lines. I know I needed it! What are the average open rates for most marketers? What kind of increases can I expect if I use your best practices?

  • Reply australia australia2741 days ago

    Here I would say my big thanks to the writer of the site for having such nice collections which are totally intresting and informative for me.Thanks a lot again!

    Radhika Basuthakur2740 days ago

    Thanks! Glad you found it helpful.

  • Reply Bryan Knowlton • 2735 days ago


    This is Bryan Knowlton over at the Daily Blogcast for Internet Marketing.

    I just wanted to let you know we discussed your blog post on our show and would love if you could help get the word out to your readers!

    Episode 058 – Google About To Attack Porn Syndicates, So Many Dating Angles, Google Glass Prescription Frames Now Available, Google Acquires AI company, 11 Email Subject Line Best Practices and Defining Your Avatar


    We found the article to be well written and decided to feature it in this episode. If you would like to provide any additional comments, you can do that directly at the bottom of the page listed above.

    Since this is a Daily Podcast, we will definitely be visiting your blog from time to time to find more great articles to discuss. If you would like to leave us a comment, question or a voicemail, you can do that on the right side of the page.

    Again, thank you for the blog post! Without it we might have not had much to talk about! :)

    Thanks again!

    Bryan & Mark
    Daily Blogcast for Internet Marketing - Because reading is hard...

    Radhika Basuthakur2733 days ago

    Hey Bryan,

    Thanks for featuring the blog post on your show. Glad you found the post useful and do come back and check out more content in the future!

  • Reply 798 days ago

    So much information to take in here; that's not a complaint its a happy observation!

    I often spend way to much time over thinking my email subject lines, trying to craft the perfect one the first time which results more often than not in a big fat fail.

    I am learning to keep it simple, and the information and guidance in this post sure help with that.

    Here is something I do if I have a poor open rate, would love to know your thoughts on this, I resend the email with a new subject line to the unopened in my email list, yes the people who did not engage with the email the first time.

    This often works really well and it gives me a second bite of the cherry so to speak.

  • Reply Steve Turner • 747 days ago

    Thanks this is a great start for anyone using email marketing.

    As a marketer I also subscribe to and receive 100 of emails which I kind of use as a personal swipe file when I see a good idea or tactic I haven't seen before.

    The most common mistake I see is whoever has composed or sent the email, obviously hasn't read it themselves. Spelling mistaks, another commonone words joined together and the absolute best for a marketer. The CTA doesn't work, or the link is incorrect.

    I always send everything I propose to send as test email to myself and read and check everything in the email.

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