Emoji use in email subject lines has gone from novelty to standard practice over the past decade. Walk through your inbox right now and you’ll spot them everywhere: 🔥 in the retail promotional tab, ⏰ next to a flash sale announcement, ✅ in a transactional notification. The tactic is everywhere. That doesn’t automatically mean it’s working for everyone who uses it.
The advice you usually get on this topic tends toward the cheerful and uncritical: emojis increase open rates, they make your subject line stand out, here are ten emojis and when to use each one. I’ve read enough of those posts and tested enough sends to have a more complicated view.
What the data actually shows
Studies on emoji subject lines show mixed results, and I think the variance is more informative than any headline number. Experian found that 56% of brands using emojis achieved higher open rates, which sounds positive until you notice the other 44% saw no improvement or a decrease. An academic study by Cohen-Vernik and Pettiette found that while emojis can lift opens, they also increase opt-outs, the very subscribers they attracted were more likely to leave. Phrasee’s 2024 benchmark study put it well: emojis tend to magnify what’s already true. A strong subject line performs slightly better with the right emoji; a weak one fails harder.
The honest read: emojis can lift open rates in the right context. They can suppress them in the wrong one. “Use emojis for higher engagement” is too simple to be useful advice.
What context matters? A few things I’ve noticed:
Industry and audience. Consumer retail and lifestyle brands tend to see positive results, particularly with younger subscribers. B2B and professional services audiences often respond worse, an emoji in a subject line can signal low professionalism to a reader who’s evaluating whether to open an email from a vendor. The same tactic reads differently depending on who receives it.
How saturated your category is. If you’re a fashion retailer and every competitor is using 🔥 in their flash sale subject lines, the emoji is no longer differentiating. It’s noise. The attention value of an emoji depends partly on how unusual it is relative to everything else in the inbox.
Where the emoji is. An emoji at the beginning of a subject line gets more visual attention than one at the end. But leading with an emoji also means that’s the first thing a subscriber sees before reading a single word, if the emoji doesn’t immediately communicate something relevant, it’s doing work against you.
The problems nobody talks about
Rendering. Emojis don’t look identical across every email client or operating system. An emoji that renders cleanly in Gmail on iOS may show as a blank box or a different character in an older version of Outlook, on certain Android skins, or in some corporate email environments. For most audiences this is a minor concern. For audiences who skew toward enterprise software, it’s worth knowing.
Spam filter implications. Some spam filtering systems flag subject lines with certain emoji patterns, particularly when combined with other spam signals like all-caps words or excessive punctuation. An emoji on its own in an otherwise clean subject line is unlikely to cause problems. An emoji stacked with “FREE!!!” and “LIMITED TIME 🚨🚨” in the same subject line is a different calculation.
Measuring impact. This is the most underappreciated problem. If you’re testing emoji vs. no-emoji subject lines and measuring by open rate, you need to account for Apple’s Mail Privacy Protection, which has been pre-fetching emails on behalf of Apple Mail users since 2021. A significant portion of your “opens” on those sends may be automated proxy requests rather than real human opens. If your list skews toward Apple Mail users, your emoji open rate data may not be telling you what you think it is. Click rate is a more reliable signal for this kind of test.
When to use them and when not to
There’s no universal rule, but there are some practical guidelines that hold up consistently.
Emojis tend to work well when the brand is already visually expressive, the audience is consumer-facing, the emoji is directly relevant to the content (not just decorative), and the subject line would be strong without the emoji. That last point matters: an emoji on a weak subject line is still a weak subject line.
Emojis tend to work poorly when the audience relationship is formal or professional, the category is already emoji-saturated, the emoji is vague or requires interpretation, or you’re stacking more than one. Two or three emojis in a single subject line is almost always too many.
The most useful thing you can do is run a genuine A/B test against your actual list, measure by click rate rather than open rate, and let your own data tell you whether your audience responds. What works for a streetwear brand may not work for a B2B SaaS newsletter. There’s no substitute for knowing your specific subscribers.
If you’re using a tool that supports dynamic subject line variants based on subscriber segments, that opens up a more interesting approach: test emoji vs. no-emoji on different behavioral or demographic segments and see whether the response differs. I’ve seen cases where emojis lift engagement meaningfully for one segment and do nothing, or worse, for another within the same list. Treating the whole list as one unit misses that signal.
Subject line tactics are one layer of email performance. How your emails reach the inbox in the first place is another, if you haven’t checked your authentication setup recently, our free Email Deliverability Test will show you where things stand.
Alterable helps email marketers add real-time personalized content to their campaigns — countdown timers, dynamic products, location-based images, and more.
