Sagar KC on Email Subject Lines That Actually Get Opened

Most emails die in the inbox. The subject line is the first filter. If it fails, the email never gets read.

I’ve tested over 10,000 emails in the last few years. Some got open rates over 50%. Others dropped below 10%. The difference? The subject line.

Here’s what I’ve learned.

1. Short wins

Keep subject lines under 50 characters. The shorter, the better.

Good:
Still thinking it over?
We saved your cart
One thing to know today

Bad:
Important update regarding your recent browsing session on our site
Let’s dive into this week’s exciting newsletter update

2. Be specific, not clever

Clever lines confuse people. Specific lines get clicks.

Don’t say:
Don’t miss this
Say:
10% off ends tonight

Don’t say:
Let’s talk
Say:
Got 2 minutes to save 20%?

3. Use numbers, questions, or urgency

Numbers feel solid. Questions pull curiosity. Urgency makes people act.

Try these:
3 things you missed this week
Forgot something?
Closes in 4 hours

4. Avoid spammy triggers

Don’t shout. Don’t write in all caps. Skip overused words like “FREE,” “WIN,” or “LIMITED TIME.”

If you sound like spam, Gmail will treat you like spam.

5. Test one thing at a time

Change only one thing per test. Subject line A vs Subject line B. Track the open rate. Use the winner next time.

Final tip: Preview lines matter too

The preview line (the sentence under the subject) helps boost opens. Don’t waste it with “View this email in your browser.”

Write something that builds curiosity.

Like:
You’ll love what’s inside
There’s still time to claim this

Good subject lines don’t need magic words. They just need to make people stop scrolling. Think like your reader. What would make you click?

That’s what works.

If you liked this read, Sagar KC on Welcome Emails: Why the First Message Matters Most

Sagar KC on Retention: Why Retention Beats Reach

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