10 AI-generated subject lines tuned for mobile inbox length, with open-rate predictions and tactic labels.
Each request returns 10 distinct lines using different psychological tactics.
Color-coded character counts — green for the 30-50 char sweet spot, amber otherwise.
Each subject line is tagged: curiosity, urgency, personalization, value, social proof.
Low/medium/high prediction based on length, tactic, and email type.
Newsletter, promo, welcome, re-engagement, launch, cold outreach — copy adapts.
Copy any subject line to clipboard — paste into your email tool.
47% of email recipients decide whether to open based solely on the subject line, according to OptinMonster's 2025 email benchmarks. The body copy could be Pulitzer-grade — if the subject doesn't earn the click, none of it matters. Yet most teams spend 90% of their time on the email body and 10 seconds on the subject.
The single biggest unforced error is length. With 60-70% of opens now happening on mobile (Litmus 2025), a 70-character subject line gets truncated to 35 chars in the iPhone preview. Half your message disappears. We color-code each result so you can pick lines that survive the mobile inbox intact.
Email is one channel. Organic search is another — and it compounds. If you're sending newsletter content that links to blog posts, make sure those posts are actually indexed by Google using IndexFlow's Bulk Index Checker. An indexed post earns traffic for years; an email blast lasts a day.
30-50 characters. That fits cleanly in mobile inbox previews (most clients truncate around 35-40 chars on iPhone, 50 on Android). Longer lines get cut mid-word, which kills curiosity. We color-code each result green when it falls in this range.
It depends on audience. B2C newsletters often see 5-15% open rate lifts with relevant emojis. B2B cold outreach usually sees a slight drop — emojis can read as sales-y or trigger spam filters. Test on a small segment before full sends. Our generator avoids emojis by default; add them yourself for B2C lists.
Personalization (using their name or company) and curiosity (a specific question) consistently win for cold. Avoid urgency tactics on first-touch cold — they read as spammy. "Quick question about [Company]" outperforms "Open Now" by 3-5x in most B2B sends.
Subject line is one of three factors. Sender name (recognized vs not) and send time (Tuesday-Thursday 10am beats Monday 6am) often matter more. Apple Mail Privacy Protection also inflates opens by 30-40% — track replies and clicks instead for true engagement.
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