Effective email subject lines

When focusing on your online reputation management goals, start with these guidelines, but don’t forget to revisit your strategies periodically. Here is what we know right now about effective email subject lines for your online review management campaign.

“Thank you”

Apparently this kindergarten takeaway is quite effective in grabbing people’s attention. Mailchimp’s study on email subject lines showed that “Thank you” has the biggest impact on open rates of all the word pairs they tested. This is fantastic news for gathering reviews, because you can legitimately thank people for their purchase or visit when requesting a online review. Straight up politeness still works, hooray!


Yes, this means addressing people by name. We have all opened one of those before, almost reflexively. Is your industry generally more casual or professional? Play with it a little bit and find out if first name, last name, or both, works better in your industry. You can personalize with 5starRocket, so we’ve got you covered. Personalization can be more than someone’s name though; it is also about timing, specific purchases, and the sender address.

SendGrid found that the timing words “yesterday” and “tomorrow” are more effective than “today.” Review requests sent out exactly one day after a visit (events, reservations, appointments) could do well to include “yesterday” in the email subject line. With product purchases, it is likely that one day isn’t enough time for someone to know if they are happy with their purchase or not, so you will need to experiment with the timing of the request, and possibly a timing phrase like “last week” would spark interest. Similarly, if you can refer to the specific purchase or service rendered in the email subject line, that constitutes personalization as well, and can also be beneficial.

Hubspot found that the personalization of the sender address is also quite important. If the request is from a specific person, it is more likely to be opened than from a more generic title. Utilizing strategies like these can really assist you in your online review management efforts.


This is a delicate balancing act. People respond positively to a sense of urgency presented with words like “important” and “breaking,” but only up to a point. If that urgency turns into demands and ultimatums, you lose them. Something subtle like “soon” is a nice place to start, providing a little nudge without going overboard.

Grammar School Rules: Capitalization, Punctuation, and Emojis.

Finally, there are a few clear winners you can rely on, for now. Use title case (capitalize every word), limit punctuation (for example, three exclamation points is a spam trigger), and experiment with using emojis sparingly.


This is the most debatable guideline, with the ideal length declared as three words by some studies and as absolutely irrelevant by others. Due to the high percentage of emails read on mobile phones however, it does make sense that an effective email subject line can’t be too long. As a basic guideline, always go for the shorter option, if you can do so without sacrificing content. Most importantly, every single word matters. Make sure each word has a purpose and be aware that changing one word can make a huge difference.

Crafting an effective email subject line is an art. There are several data studies by email marketing specialists showing what has worked well in the past. But, not one of them can break it down into an exact science. There is even Industry bias. So, there are not repeatable, fail-proof steps to follow. The above guidelines are based on past performance of email marketing techniques, but the evolution of email marketing operates at high speed. Staying up with the trends is important, and we will keep you updated.

The real key to composing a effective email subject line is to keep innovating. Test new ideas and variations to stay out in front of the trends and guidelines. Nothing works indefinitely, even for the exact same demographic. Get creative with new approaches and test them on segmented audiences.

If this sounds daunting, don’t despair. Requesting a review is a relatively straightforward mission. You have to start somewhere and these guidelines will get you going. Success in using 5starRocket is defined by getting more opened emails, and ultimately more reviews, than you had before you started using us. It is about moving in the right direction, little by little.

Experimentation is going to play a huge part in finding the email subject line that gets the most online reviews for your particular business. At the end of the day though, it isn’t as complicated as it may seem at first glance. Short, sweet, and to the point will get you started. A sense of adventure will take you the rest of the way with email subject lines.

Customizing your account is easy. Get in control of your online reputation and start writing effective subject lines with a 5starRocket account.