Subject Line & Deliverability Tester
Test your subject line length, emoji count, and spam keywords before sending.
Proven B2B Subject Line Templates
Need inspiration? Try customizing one of these proven, high-converting templates.
Suggested Preheader Text for Your Subject Line
Pair your subject line with one of these complementary preheader snippets to boost open rates and maximize inbox preview impact:
6 Battle-Tested Tips for Higher Email Open Rates
Proven best practices to get your emails noticed and opened in crowded inboxes.
Target 30 to 50 Characters
Over 60% of emails are opened on mobile devices where long subject lines get truncated. Keep your core message early in the line.
Front-Load Key Value Words
Place your most intriguing word or benefit at the beginning so fast scrollers catch the value proposition instantly.
Avoid Spam-Flag Trigger Words
Words like "100% free", "guaranteed", "$$$", or "act now" trigger automated ISP spam filters and lower deliverability.
Use 1 Strategic Emoji
A single relevant emoji can increase open rates by up to 15% by standing out visually, but excessive emojis look spammy.
Always Write Preheader Text
Preheader text acts as a secondary subject line. Use it to expand on the subject line's hook rather than repeating it.
A/B Split Test Variations
Test question-style vs statement-style subject lines on a small sample segment before broadcasting to your full list.
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Frequently Asked Questions
Everything you need to know about subject line optimization and inbox deliverability.