Survey Email Subject Lines for Great Response Rates

People are managing ever-increasing volumes of daily email messages. When they skim their lists of unopened emails they look at two things, who the emails are from and the email subject lines.

Messages which are recognised as spammy, uninteresting or suspicious will be immediately consigned to the trash bin. Busy people do not want to waste their time opening and reading email messages that are not beneficial to them. The right email subject line makes all the difference.

According to the Convince and Convert blog 35% of recipients will open an email based solely on the subject line.

Encouraging recipients to open their survey emails is a vital step in getting them to actually take part in your survey. So the subject lines of your survey invitation emails need to work hard to return great survey response rates.

Avoid spam trigger words

When composing email subject lines it is vitally important to consider the triggers used by spam filters to identify potentially spammy email messages. The last thing you need is for your survey invitation emails to be automatically identified as spam and filtered out so that they will never be seen or opened.

Luckily there are lists of keywords which can trigger spam filters. It’s worthwhile reviewing these terms when composing your email messages. For example, the following are just a few ‘red flag’ words.

  • Free installation
  • Amazing stuff
  • Cash bonus
  • Free preview
  • No investment

Email Open Rates

Email open rates are influenced by a multitude of factors. Rates vary from industry to industry and are highly affected by the type of email message. For example, routine newsletter emails tend to have far lower open rates than transactional emails from the same sources. It’s a good idea to gain an appreciation for what are typical email open rates in your industry. For example, email statistics for 2018 indicate the following, average industry-specific open rates.

  • Health care: 35.54%
  • Non profits: 34.44%
  • Publishing: 36.59%
  • Internet marketing: 18.05%
  • Automotive: 23.6%
  • Technology & High Tech: 24.66%

As can be seen, the typical open-rate for internet marketing industry email messages is only half of the open rate for publishing industry email messages. It’s worthwhile being aware of email open rates that apply specifically to your industry.

Be Simple and Specific

Make your email subject lines clear, simple and specific. Don’t be tempted to use cryptic, clever, creative email subject lines as these are far more likely to put people off. A clear, specific email subject line is far more likely to be opened than an email with a subject line that requires thought.

Some time ago published detailed statistics derived from their own email strategies. They found that ‘clarity trumps creativity’, and very significantly. Clear email subject lines resulted in 541% more clicks than creatively composed subject lines.

Genuinely effective survey invitation email subject lines succinctly provide everything that the recipient needs to know.

  • Tell them what the purpose of the survey is.
  • Tell them why they should take part in the survey.
  • Make it clear what’s required from them and how long it will take.
  • Provide time details such as how long the survey is running and when they need to respond.

Keep it Short

Long, rambling email subject lines are a bad idea. They may not be displayed completely and correctly in the recipients email client and they are not generally liked. Short and sweet is what works best.

The influence of email subject line length on email open rates has been extensively tested and retested. An updated study by has reconfirmed that email subject lines of 6 to 10 words drives the highest open rate of around 21%. Here are the statistics:

  • 6 to 10 words: 21% open rate
  • 0 to 5 words: 16% open rate
  • 11 to 15 words: 14% open rate
  • 16 to 20 words: 12% open rate.

The key point here is that subject lines in excess of 10 words tend to attract increasingly fewer clicks as more words are used. It has also been recommended that the subject line character count should be in the region of 30 to 50 characters.

Personalize and Incentivize?

Personalization is highly effective. Personalized email subject lines can increase open rates by over 60%. For example:

Julie, we need your feedback on ticket 1423

How did Stefan do on this morning’s call?

Personalization conveys importance to the recipient. It makes your survey request email look more like a personal invitation, which people like.

It can also be useful to offer an incentive. For example:

Julie, tell us how you feel in one click and win

Stand Out from the Crowd

You will no doubt have received many survey invitation emails with subject lines like these:

  • Rate your experience
  • Tell us what you think
  • Your opinion matters
  • Share your thoughts with us

It is always worth considering how you can make your survey invitation email stand out from the crowd, either using different phraseology or specifics.

  • Did we do well?
  • Did we make your Wednesday better?
  • Your input
  • Your feedback

A couple of simple but effective techniques that can differentiate your emails from others in a recipient’s inbox are to use punctuation or unicode symbols.

Tests have demonstrated that constrained use of punctuation in subject lines can have a beneficial influence on email open rates.

  • A full stop (period) at the end of subject lines can increase open rates.
  • Using a question mark has been found to have no beneficial impact on email open rates.
  • The exclamation mark can have a beneficial impact on email open rates, but must not be overused.

The key recommendation regarding punctuation is to use it sparingly and don’t use it in every email subject line.

Have you have ever noticed interesting, unusual characters such as stars, hearts and airplanes in email subject lines? These are unicode characters which can, when used cautiously, improve email open rates.

A study by found that email subject lines which contain the friendly snowman symbol were highly effective in driving increased open rates. But that does not mean that it would be appropriate to use this symbol in all email subject lines. And it is worth noting that the inclusion of some symbols had a significantly negative impact on email open rates, so its worth testing.

Another emerging trend is the use of emojis in email subject lines. An Experian study determined that including an emoji in email subject lines results in a 56% increase in email open rates, compared with plain text subject lines.


Different emojis resulted in various open rates. Emoji images immediately capture the attention of a recipient and can save space by using fewer characters; for example a ‘heart’ emoji instead of the word ‘love’. Emojis, such as smiley faces, are also a great way to convey emotions which is often very engaging. Here are a few examples.

This email message uses a running figure emoji to illustrate the email topic.

emoji in email subject line

This next example uses a lipstick emoji to illustrate the email subject.

lipstick emoji in email subject line

And this next example uses a representative delivery truck emoji in their order update email message subject line.

order update email subject line with emoji


Optimal Timing

Optimally timing your survey invitation request can be important. People often ask: ‘When is the best time to send an email?’ Generally, if your aim is to survey people after a specific event or action (such as a customer service request or a purchase), then you should invite their survey responses as soon after the event as possible. Don’t leave it for days or weeks because they will not remember how they felt about their experience.

Many studies have been carried out to evaluate how people behave and respond to email requests at different times of the day and different days of the week.

Which day is best to send emails?

  • Tuesday: Multiple studies have shown that Tuesdays are by far the most effective day for email communications.
  • Wednesday: Found to be the second most popular day on which to send emails.
  • Thursday: Following on from Tuesdays, Thursdays are a good choice for a second wave of emails.

When is the best time to send emails?

  • 10 a.m. to 11 a.m. Late morning has been found to be the most effective time period in multiple studies.
  • 8 p.m to midnight. Interestingly, statistics show that a lot of emails are read late in the evening, just before people go to bed.
  • 2 p.m. Early afternoon is the next most popular time for emails to get opened.
  • 6 a.m. Interestingly, many people appear to start their day by checking their emails from bed, very early.

Regarding time zones, it’s important to choose the time zone in which the majority of your target audience reside.

Another important aspect of timing is how quickly a recipient opens your survey invitation email. To push people to open your message immediately it can be useful to introduce some urgency into your subject lines. By using compelling language in your email subject lines you can prompt recipients to act straight away.

Julie, tell us how you feel right now for a super prize!

Test and Test Again

Statistics and data from various studies is enormously useful but does not necessarily reflect what will work best for you and your industry. The best way to determine what is right for your needs and your objectives is to test, and then, test some more.

  • Carry out A/B split testing of your email subject lines.
  • Trial sending emails at various times on different days of the week.
  • Test various forms of incentive.

By gathering and analysing your own data you will be able to optimise your email subject lines for the very best survey response rates.

Don’t Do This

We’ve provided what we think are some realistic, actionable recommendations which will improve your survey invitation email open rates and response rates. Here are a few key things to avoid.

  • Don’t use ALL CAPS in your email subject lines and don’t overuse uppercase characters. They look like shouting and can have a negative impact on email open rates.
  • Never lie or be misleading in your email subject lines.
  • Avoid spelling errors. Always spell-check your email subject lines.
  • Don’t use email subject lines which are overly long.
  • Don’t use spammy words in your subject lines.

Want to improve your customer survey response rates? Customer Thermometer’s 1-click survey will up your feedback game. Send yourself an example:

How did we do today example