A lot goes into crafting the perfect subject line.

The subject line of your email is one of the first impressions someone gets from your brand, especially when you’re sending them an email for the first time. After the ‘From’ name the subject line is the next item that influences whether or not your reader is going to open your email.

Will your customer or potential customer open your email right away?

That’s where personalization in email subject lines comes into play. Are you on a first-name basis? Do you know what their interests are? Using what you already know about the customer in your favor should be your No.1 priority while sending marketing emails. Personalizing your subject line can be broken down into six broad categories, which we’ll detail below.

1. First names

Recognizing your customer and giving them attention (albeit via an email) usually works in your favor. Experian reports that personalized promotional emails have 29% higher unique open rates and 41% more unique click-through rates. Using your reader’s first name in the subject line of your email makes them feel valued. Out of the dozen emails you receive in your inbox daily, the ones that usually catch your eye are the ones that mention your name in the subject line. The same goes for all your readers and customers.

Note on open rates: Apple’s Mail Privacy Protection feature, which was released on September 20th, 2021, has made email open rates less reliable. While historical open rate data can still provide valuable insights, we recommend marketers focus on other email marketing metrics, like click-through rates and conversions, when measuring their success going forward.

examples of personalized subject lines

2. Interests

Sending an email with a subject line that talks about dog supplies to a cat owner or vice versa is one of the biggest email marketing sins. It just goes to show that you don’t know your customers at all and this might get them to unsubscribe from your mailing list. Use your knowledge of your customers to talk with them one-on-one in your emails, taking your personalization to the next level. Your subject lines should let readers know that there’s something in the email they’ll find relevant to them.

3. Birthdays and Anniversaries

According to Experian Marketing Service’s subject lines with a simple “Happy Birthday” or “Happy Anniversary” mention have more engagement on average. Click rates are significantly higher when you take that extra step for your customers. Don’t know your customers’ Birthdays/Anniversaries? Send out a survey. Include a discount or a free trial of your product or service in return for their time completing the survey (everyone loves those!).

What’s nice is that you can automate birthday emails knowing you’ll get high engagement with them. You can also celebrate your ‘Brand Birthday’ with your customers. The more, the merrier.

4. Transaction history

An offer for an irrelevant product is useless to the recipient. So tap into your customers’ transaction history to figure out what they’re most likely to buy. Send them an email with the subject line concentrating on related products and services and watch them return to your site. Customers look to see if you are paying attention to their needs and if you’re willing to take that extra step to convert them into a returning paying customer.

Email subject personalization example using transaction history.
Here’s another example from my inbox. You can see which emails I’ve opened – Emails that make me curious, create a sense of urgency, and remind me to check out before my favorite products are sold out.

5. Urgency

The fear of missing out or FOMO is something that plagues us all. Subject lines that say things like”Only Four samples remaining” or “New tax implications go live Tomorrow!” create a sense of urgency and motivate people to open them. But these need to be used moderately. If you’re sending an email a week saying, “Only 4 items left”, people are going to start to wonder why you’re so understocked all the time.

6. Location

Sending emails to customers about summer dresses when it’s still snowing in their part of the world is silly, and reeks of bad research on your part. However, a properly targeted email with a subject that reads, “Clearance Sale: 80% off on Winter Coats” might get a customer to open and click. Small businesses and nonprofits can use localization to create email subject lines that interest readers based on what’s happening around them.

Some other things to consider when personalizing your subject lines

Avoid using common phrases that trigger spam filters in your subject lines. Using these words can make your email land in the spam folder. Email subject lines with all caps and excessive punctuation marks also have a higher tendency of landing in spam.

Keep character limits in mind. With an increasing number of emails now being read on mobile devices, you need to make sure your customers can read the entire subject line. At Constant Contact, we typically recommend four to seven words or 40 characters for subject lines.

Use personalized subject lines to use to get more people to open your emails and take action!

Remember: A subject line should be a tease of what your email contains and why it’s valuable to each person on your list. The more relevant and personal your subject line is to the reader, the more likely it is to motivate them to open.