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6 Email Subject Line Tips to Boost Open Rates (Backed by Data)

Alex Middel
August 30, 2016

You have a perfect landing page with a conversion rate of over 15%. You have highly engaging email copy that entices your audience to click through to that landing page. But if your email subject line isn’t getting people to make the initial click, nothing else really matters.

For some apartment marketers, an email subject line is an afterthought. They’ll go with the first thing that comes to mind and move on. However, your subject line is arguably the most important part of an email marketing campaign because it’s what initiates the process.

According to data from Convince & Convert, 33% of email recipients open emails based on subject line alone. So if your subject lines are boring, dull or look like spam, you could be losing out on a third of your potential leads. But you can fix it!

Follow these six data-driven tactics to boost your open rates and get more eyes on your emails.

1. Think Mobile

When you’re crafting your email marketing campaigns, you’re most likely doing it from a desktop or laptop. So when you preview your emails and subject lines, you’re looking at it on a full-size view. However, 53% of emails are opened on mobile devices.

 Emails Opened in Mobile

The average mobile screen can only fit 4-7 words of an email subject line at the most. That means if you’re using long sentences as your subject line, there’s a good chance your email subscribers aren’t seeing it.

Here’s an example of how the same subject line looks on desktop vs. mobile.


 Desktop Email Subject Line


 Mobile Email Subject Line

Notice how the mobile version has been truncated, so it’s less readable and not as compelling as the desktop version.

To combat this, make your subject lines succinct. Brevity is a skill top copywriters accel at because they’re able to take longer thoughts and ideas and compress them into a few words.

The key is to make what your email is about as clear and simple to understand as possible, while still capturing the reader’s interest.

 Succinct Email Subject Line

In the email above, the company makes their message very clear, while making it enticing enough to click through.

Your email marketing software should have an option to preview your campaigns on a mobile device and desktop. Make sure your subject lines are readable on all devices before you hit send.

2. Avoid Using These Words & Phrases

Hubspot researched which email subject lines received the most and least amount of clicks. In that data, they discovered subject lines with certain keywords tend to get fewer opens:

  • Emails with "You" were opened 5% less
  • Emails with "Quick" were opened 17% less
  • Emails with "Meeting" were opened 7% less
  • Emails with “fw:” were opened 17% less

Those are just some of the keywords people avoid. But another issue you could run into is having your emails sent to the spam folder before your subscriber ever reads them. Email providers have filters set up to catch potentially spammy emails and throw them in the junk folder. These filters work based on certain keywords commonly associated with spam.

Mailup compiled a list of the top phrases anti-spam filters use to detect spammy emails. Many of them are associated with scams and junk products, but here are some of the more general phrases on the list that all marketers should be cautious of:

  • No investment
  • free preview
  • Mortgage rates
  • Earn extra cash
  • Please read
  • Pre-approved
  • Print out and fax
  • Order today
  • Have you been turned down?
  • Quote
  • Sales

This doesn’t mean you should never use any of these phrases in your email subject lines. Depending on the context you use them in and the relationship between your company and the recipient, you could be perfectly fine using some of these words and phrases.

But, if you’re sending cold emails to a list you purchased or are sending an email to someone for the first time, you may want to tread lightly.

3. Personalize Your Subject Lines

When you receive an email that mentions your name in the subject line, how often do you ignore it? If you’re like most people, you probably open it most of the time because it’s addressed to you.

According to data from Experian, personalized email subject lines received 29% higher unique open rates and 41% higher unique click rates. On top of that, adding personalization to your promotional emails can lift transaction rates and revenue per email six times higher than non-personalized emails.

 Unique Open Rates for Emails with Personalized Subject Lines

One of the easiest ways to add personalization to your email subject lines is to use the recipient's name. Although it’s easier to just ask for a lead’s email address, going the extra mile and getting their first name too can help you in the long run.

 Personalized Email Subject Lines

Some email marketing companies like Mailchimp even allow you to customize the “To:” field if you have your subscribers’ names. This will dramatically decrease the chances of having your emails end up in the junk folder.

 Mailchimp Personalized To Field

If you don’t have names for the people on your email list, you could also add personalization by using their location. This is a very common tactic used in the apartment marketing industry.

 Localized Email Subject Lines

The more a recipient feels like an email was personalized just for them, the more likely they’ll be to open it.

4. Split Test

We mentioned the importance of split testing (or A/B testing) for Facebook ads and in landing pages. Split testing is also important for email marketing because it allows you to try out multiple subject lines to find your winners and losers.

 Email Split Testing

Testing multiple headlines gives you insights into the habits of your list. You can test things like the ideal length of a subject line, types of punctuation, keywords and much more.

Instead of sending the same email to everyone in your list, get in the habit of writing at least two different subject lines and compare the open rates for each. When you’re split testing, your subject lines should be the only variable. The day and time you send your emails, and the body copy, should be exactly the same for each version.

Here’s a tip. If your email marketing software allows you to, don’t split test an email to your entire list. Send your variations to a segment of your list and see which has the best open rate. Then send the winning version to the rest of your list.

This way if one version dramatically outperforms the other, you’re not sending an underperforming email on half your subscribers. Optimizely did an A/B test on a subject line and received 13.3% more email opens.

5. Segment Your List

Piggybacking off the previous tip, segmenting your email list is another great way to boost open rates.

Your email subscribers may not have all signed up under the same circumstances or have the same needs. So why send out the same emails and subject lines to all of them?

For multifamily marketers, some good ways to segment your list could be:

  • Renters vs. Non-Renters
  • Tenants with pets
  • Number of bedrooms
  • Length of tenancy
  • Which floor-plan they have
  • When they moved in

The goal of segmenting is to allow you to send more targeted emails, which will ideally increase your open rate.

For instance, let’s say you have an email list of 100 tenants, 20 of which have dogs. So you send an email to that entire list with the subject line “[First Name] Looking for Dog Walkers in Lakeview?”

That email will be irrelevant to 80% of your email list, so a majority of them won’t open it. Even if all the dog owners open the email, the highest open rate you would get is 20%.

But if you only sent that email to the dog owners, and 15 of them open the email, your open rate jumps to 75%. You could be sabotaging your own open rates by not segmenting your list!

Email on Acid found 39% of marketers with segmented email lists achieved higher open rates. On top of that, 28% had lower unsubscribe rates and 24% had increased sales leads.

 Email List Segmenting Stats

6. Use Passive Words

After analyzing an email database of over 1,000,000 subscribers, Jens Jakob Andersen found that subject lines with aggressive CTA’s don’t perform as well.

According to Jens’ data, subject lines with passive expressions like “read more” and “learn more” receive a 9-14% higher open rate than subject lines with aggressive expressions like “buy now” and or “buy here.”

That shouldn’t be too surprising considering a lot of the words in the anti-spam filter list we mentioned earlier swayed towards the more salesy end.

Save your call to action phrases for the body of your email. They’ll be much more effective there, since your goal is to drive people to click through to your landing page or website. Your email subject line isn’t meant to get people to buy, it’s to get them to be interested in what you have to say.

Don’t Settle for Low Open Rates

Use all the tips above to improve your email marketing efforts. Once you start to learn what works best for your audience, you’ll see your open rates increase in no time!

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