As with most things in the digital marketing world, the criteria for “good” and “successful” changes often. With spam filters constantly advancing, you’ll need to stay on top of what triggers them in order to continue getting into inboxes. You’ll also need to stay on top of your consumers’ behaviors and interests in order to continue getting opened, as engagement affects deliverability.
With that in mind, here are 7 ways to prime your subject lines for success:
1. Keep them short
Subject lines should always be concise. Think of your email campaign as breaking news and your subject line is the headline. Prioritize getting your point across, and if you’re able to add a clever or creative twist (or even an emoji) without jeopardizing the length and integrity of the message, then absolutely do so. You can always use preview text to elaborate a bit more on the contents of your message.
2. Don’t use spammy words
A subject line often functions as a call-to-action that inspires urgency or curiosity, but there are some words (actually more like 474) you should avoid because they’ll trigger spam filters to flag your email as suspicious. Basically, if the words you want to use come off as pushy, too-good-to-be-true and just blatantly gimmicky, replace them.
On the topic of spam, don’t write your subject line in all-caps. You’re basically yelling at spam filters to flag your message.
3. Don’t lie or mislead
The goal of email marketing is to build a rapport with your customers in which trust is a key player. Don’t jeopardize that by making a false promise in your subject line. Sure, it may increase opens for that specific campaign, but your subscribers will feel irritated and take it out on your future campaigns by deleting them, moving them to junk or simply never opening them. Because spam filters consider the engagement of your previous campaigns, these actions can seriously harm your email marketing efforts. Honesty is the best policy.
4. Ask questions
When executed properly, questions can be some of my favorite subject lines. They often pique my interest, and my curiosity inevitably leads to an open. So, how does one properly execute a question as a subject line? Think about how your product could benefit someone and frame the question around that.
Similarly, for publications and newsletters, think about the overall question your main content answers, and ask that question as the subject line. Even if it’s a far-fetched question, by using it as the subject line, you’ve piqued the curiosity of your readers.
5. Include deadlines
A sense of urgency is completely fine when it’s not aggressive, so mentioning that a sale ends tomorrow or counting down the days until a new product's release or restock can successfully inspire your subscribers to take action without triggering a flag from spam filters.
Thanks to list segmentation, you can go beyond including your subscriber’s name in the subject line; although that works well, too. You can group subscribers by shopping behavior, geographic location, birthday, interests, age, gender, job industry--I mean the list just goes on--to send super-specific campaigns with super-specific subject lines. This practice will help ensure high open, click-through and click-to-open rates, as well as low unsubscribe rates.
7. Numbers are your friends
I’m sure you could go to your inbox right now and find a subject line that includes a number. If it’s not a discount or price, it’s probably part of a list. Numbers help capture attention because they stand out among the sea of letters. Plus, content presented in a numerical list format, which most people know to be easy reading, makes these emails unstoppable.
Lists are great for newsletters and blogs, but they also work well for promoting products and services.
If you have the opportunity to use a number, take advantage. Throw those AP Style rules to the wind when it comes to dates, prices, discounts, days/hours remaining, etc. Using numbers will also save you precious real estate within the subject line while grabbing subscriber attention, subsequently increasing your campaign’s engagement and boosting deliverability for future campaigns.
To wrap it up
Like sender names, subject lines can both negatively and positively impact your campaigns. These 7 practices are generally successful, but to make sure they really work for you, it’s important to keep an eye on your analytics. Specifically, your open and click-to-open rates will let you know whether your subject line has truly succeeded.