Dos and Don’ts for writing effective email marketing subject lines


Email subject lines are exactly like real life first impressions – if you make a bad impression, you’ll be avoided, so if your email subject line is bad, your subscribers will never open your email nor your future emails.

It’s particularly important when you’re sending email newsletters to subscribers – they know you’re trying to sell them something so they’re naturally cynical when receiving emails from you, even if they alone subscribed. Thing is, we all love to buy and love to try new things and take advantage of others’ knowledge and products. We just don’t like to be sold to, we want to have some control.

When writing a newsletter to send to your subscribers, certain keywords in the subject line can encourage or discourage the receiver from reading it and studies have been made to test exactly how people react to which words. We read a number of studies and made this short list with the most important keywords that we hope will be of use to you.

Don’t use:

  • “Register” – According to the Adestra 2013 Report, it has the worst open rate number of any keyword. If you’re asking someone on their email, as emails are already considered something private, to give out more of their personal information, you’d better have a great reason for asking.
  • “Don’t miss” – we can almost see people’s eyes rolling when they get an email with this subject line. It’s great only when it’s truly a rare occasion and not just a buzz.
  • “Re:” or “Fw:” –  you might think the person is more likely to open it when they think they’ve already contacted you and some (fewer and fewer) indeed do, but this may very well be the last email they open from you.
  • “Help” – at a mere 2.5% open rate, it seems we’re not very altruistic.
  • “Donate” – 11.6% open rate, progress from “Help”, but still not a good word to use in the subject line. Keep it for the actual message after you’ve piqued the reader’s interest.
  • Exclamation marks!!! Don’t they sound a little fake?

Be wary of:

  • “Free” or fantastic offers – they’re great right now and will bring you gains, but they hurt your brand in the long term as clients won’t be willing to pay the full price and will just wait for the next offer. “Free” also tends to trigger spam filters.
  • “Sale” and specifying a percentage off in the subject line – they only have an 1.9% open rate according to Mail Chimp, but Adestra noticed a 10.5% open rate on emails with a percentage off in their 2013 Subject Line Analysis Report. Interesting to see such varying results. Still a pretty small open rate no matter which study you listen to, so it’s best to use the words sparingly and when you have a truly great sale.

So what works?

  • “Learn” – offer people value as we all want to know interesting or useful things. It’s the hardest thing to do, but the one that brings the most results.
  • “Alert” – but don’t use them when they don’t apply or your email will have the same fate as “RE:” and “FW:”.
  • “Free Delivery” – if you’re a store owner, definitely look into providing customers with free delivery at all times to make it easier for them to calculate the final costs.
  • “Latest” and “New” – as long and they’re not used too often and actually mean new content, they have a good open and click rate, especially “Latest”.
  • Make sure your subject lines have less than 50 characters – they have the best open rate.

Offering something of value in the email and stating in the subject line exactly what that is, without any flourishes or attention-grabbing words, tends to be the best (and honest) approach.

What else?

Now that we covered some of the most important keywords for subject lines, let’s take a quick look at a few things that will make actual email attractive to readers:

  1. Always have important information or quality and relevant content. Great content is the top most important thing in email marketing campaigns.
  2. Freebies – answer your subscribers’ “What’s in it for me?” question once in a while. Templates, tools, ebooks, whatever you can offer considering your industry, don’t be afraid to treat your subscribers with them once in a while. Just, again, be wary of using the word “Free” in the subject line.
  3. If possible, let your customers choose one or more types of emails to receive to make sure they get exactly what they’re interested in. 60% of marketers do not give subscribers this option.
  4. Set a regular schedule for your newsletters so your subscribers will know when to expect them. Daily and weekly emails work best according to some studies, but we know how annoying daily emails can be if they’re not interesting or relevant enough to us to actually want every day. A store we know found out their newsletter had the best results when sent every 3 weeks, people unsubscribed when they sent weekly. So experiment with what works for your particular business. Saturday to Monday are usually the best days for getting your newsletter read.
  5. Make sure that your emails (and website) can be opened on a mobile device – smartphone use keeps gaining more ground and 61 percent of users are unlikely to return to a mobile site they had trouble accessing.

Creativity also goes a long way, so as long as you don’t seem salesman-ish, try new things, interesting offers, excellent content and experiment as much as you like while keeping track of what gets the best results.


To prove the fact that content is king and going against the grain can be effective, OkDork and BidSketch do something great with their newsletters – they both send extremely informative emails every few days with well researched advice, not too short, to the point and – surprise surprise – plain text only. It works well because they’re focusing entirely on the content they’re delivering.

That works for them, other businesses get more from using bright and colorful images and imaginative designs – all of us usually subscribe to and expect pictures, prices and offers from electronics stores, book stores or clothing stores. No clothing store is going to have a successful email marketing campaign by using text only newsletters, but if one ever does, I’m looking forward to hearing the tale.

If you have tried any of these keywords in your email marketing campaign or had success with others, post a comment as I would love to read about it! If your campaign was so-and-so, shoot me a message and we’ll check out what didn’t work together.




Subscribe to our newsletter for more freebies, articles and other good stuff we'll send out from time to time.