The 4U Formula: How to Write Subject Lines with 50%+ Open Rates

You spend hours crafting the perfect email copy. You design a beautiful layout. You hit send. And then... nothing. Crickets.

If your subject line fails, your email fails. It doesn't matter how good your offer is if no one sees it. At UrEmail, we've analyzed over 1 million B2B emails. The top 1% all share one thing in common: they use the 4U Formula.

The 4U Formula Explained

Originally coined by copywriter Melanie Duncan, the 4Us stand for:

• Urgent
• Unique
• Ultra-specific
• Useful

You don't need all four in every subject line, but if you can hit 2 or 3, you're golden.

1. Urgent

Urgency forces a decision. It tells the reader "Act now or lose out."

2. Unique

The inbox is a crowded place. If you sound like everyone else, you get deleted. Uniqueness piques curiosity.

3. Ultra-Specific

Vague promises breed skepticism. Specificity builds trust. Use numbers, names, and concrete details.

4. Useful

Ultimately, the reader asks "What's in it for me?" Your subject line must promise value.

Putting it all together

Here are some winners from our recent campaigns:

• "Your subscription is expiring" (Urgent + Useful)
• "The $100M question" (Unique + Specific)
• "212 blog post ideas" (Specific + Useful)

Conclusion

Your subject line is the gatekeeper. Treat it with as much care as the email body itself. Test these 4Us in your next campaign and watch your open rates climb.