Email subject lines

Exclusive Bulletin: Write your subject line so that your emails get read

This past week I had the good experience of dealing with the support staff at SendMail, a mail relay company.  Because their whole business is sending out other peoples’ emails, they know a whole lot about the factors that let emails get through the myriad spam filters used by ISPs who receive email for their customers.

The support person and I were watching a mailing of a newsletter that was going out to some 13,000 subscribers.  All went well, but I received some advice–in the subject line, avoid words that are in all caps, and don’t use multiple special characters such as ! or &, in order to avoid being classified as spam by ISP filters.

This caused me to realize that, while I knew some general guidelines about writing email subject lines, I hadn’t studied it in detail.  So I decided that both you and I could use some guidelines, taken from wisdom offered by industry luminaries, distilled by my experience of years of actually doing it and looking at results.

Hubspot tells us that 33% of email readers decide whether to open or not based on the subject line alone.  That gives us motivation to pay attention to this topic!

Subject lines have two jobs. First, they have to get through ISP spam filters, or no one will see the email.  Then they have to get through the “filter” of the recipient’s mind so that the email gets opened, read, and acted upon.  This newsletter gives you some ideas on how you can accomplish both with your emails.


One topic on which experts disagree is personalization in the subject line.  Some say that placing a first name in the subject line makes the receiver think the email is intended specifically for them and will increase open rates.  Another expert says that the technique is over-used, our friends don’t put our first names into subject lines, and when we see our name in the subject line we’re likely to recognize it as machine-generated.

Personally, if I see my first name in an email subject line there’s little chance that I’ll open it, because I realize that it’s an overworked advertising tool, and there’s likely to be little personal content inside that email.  Understand that the balance of expert opinion doesn’t agree with me on this issue, although some experts I respect such as Nielsen Norman Group do.

I think if the recipients for your email are adults with some computer experience, adding personalization in the subject line is a bad idea.  There are creative ways to use it in the body of the email, though.  For example, if you know how many times a guest has visited your hotel, you can say “You’ve spent a total of 83 nights in our hotels, so we’d like to offer you some special benefits.” This provides the reader with personal information they may not even have known.

Short and Sweet, Emphasis on Short

Our same friends at Hubspot tell us that as many as 40% of emails are opened first on mobile devices, and that fits with measurements that I’ve made with my own and clients’ emails.  Do you want to read something long on your phone?  No, you don’t.  So Hubspot recommends subject lines of no more than 50 characters. Many industry experts agree with that recommendation.

I don’t.  While you might not want to read a long subject line on your phone, if the part of it is interesting it might motivate you to open the email at least to read the rest of the subject line!  A quite extensive study by adestra supports the use of longer subject lines.

With regard to word count, adrestra’s study shows that there are two sweet spots–less than 5  words and more than 15 words.  If you can convey the point of the subject in 5 or fewer words, do so!  But if you need 15 or more, that’s fine too.  The middle ground of 5 words to 15 words is not as good, and is to be avoided.

With regard to the “sweet” part of this guidance, think about the person receiving your email.  Especially, understand that they are not part of your record-keeping system.  They don’t care that “Order number 84756633 has shipped”; they care that “Your order from Smith Co. has shipped”.  You may use an order number or a reservation number to track the transaction internally, but expecting your customer to use that number is to force them to be part of your records for you.

If you’re sending newsletters should you include the word “newsletter” in the subject line?  I’ve gone back and forth on this issue, believing that perhaps if people see it’s my newsletter, and they are subscribers, they’re more likely to open it.  On the other hand, it takes a lot of space out of the subject line, especially when you add whose newsletter it is.

adestra’s study shows that the use of the word “Newsletter” in the subject line lowers the open rate significantly.  Perhaps the term has been overused.  Here is their table on the impact on opens and clicks of certain words.  Notice that we still have some good words to use in the subject line:  Bulleting, Alert, Exclusive, Special.

This table is for the publishing sector:

Effect of subject line word choice on open rateThe B2C sector, below, has some interesting findings.  We need to beware the use of free, half price, and especially coupon!  However, if instead of a coupon we offer a voucher, our open rates will soar.  And, of course, who can resist two for one?  My wife and I have booked several cruises on the strength of two for one offers.  Note the importance of latest; of course, everyone wants the latest, best information.  I’m going to use the word latest in the subject line for this newsletter, and will measure its impact.

B2C word choice in subject linesUse A Familiar Sender Name

Hubspot found that an email from a person’s email address was associated with more opens than an email from an institutional email address.  Everyone would rather communicate with and be addressed by a real person, not a department or function.  And they reflect that in their open rate.  Choose a person in your company to be the official source of these emails, especially for anything that repeats like a newsletter, and be consistent about it.

Never, never, never use as the source.  First, it tells the reader that you don’t care what they think about this communication, and if they reply you’re so rude you won’t even read their reply.

Be Concise

Many readers are scanning subject lines on their phones, deleting emails that they don’t want to see again.  So be sure to tell them what’s up using as few words as you can.  Make the content as relevant as you can.

If it’s general information, try to say something about the benefit, not just the topic.  For this newsletter, the benefit would be getting the newsletter read, so a subject line might be How to get your newsletter read.  Including the good words from the table, it could be rewritten as Exclusive Bulletin:  How to get your emails read.

As an experiment, I’ve used just that subject line for this newsletter!  If you’re reading this as a newsletter, then it worked.

Don’t use ALL CAPS or overuse exclamation points!!!!!

My helpful support person at SendGrid pointed out that a number of companies who run mail servers that receive email on behalf of their customers use spam filters that use all caps and lots of exclamation points in the subject line as one way to identify spam.  And if they classify your email as spam, then their customers won’t see it.

This works twice, actually.  In addition to the spam filters, customers actually prefer the subject line to be written in sentence case, with the first letter capitalized and then only proper nouns capitalized.

Consider Preview Text

A number of email clients provide the first line or so of your email alongside the title, so make sure your opening sentence in the email encourages recipients to open it.

Use a Deadline

If it’s appropriate, a deadline can motivate the recipient to open and read an email.  If there’s an opportunity that goes away, or a meeting or event on a specific date, put that date in the subject line, to let the recipient know that they need to respond or lose an opportunity.

A deadline can be an important motivator to open an email.

What If It’s Not Opened?

Even if your email isn’t opened, don’t despair!  If the recipient doesn’t unsubscribe, just receving your email with your company name and the piece of your message that’s in the subject line has reminded them that you exist for them to do business with.  If they felt there was no possibility of doing busiiness  with you, they’d unsubscribe.

As long as they don’t unsubscribe, even unopened emails are doing a marketing job for you, and at far lower cost than other forms of advertising.

The Bottom Line

Pay attention to what the recipient sees on your emails–the sender and the subject line–to get your message read and acted on.

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