1Pick a scenario
Cold email, sales, follow-up, meeting request or formal business — each has its own proven patterns.
Free sales email subject line generator
Sales email subject lines
Sales email subject lines
that get opened
Generate proven sales email subject lines and score your own for length, spam triggers and open-rate killers — instantly. Free, no sign-up.
No sign-up required
Spam-word check
Instant scoring
A great subject line is wasted on the wrong list.
Flow AI finds your ideal buyers and runs personalised email and LinkedIn outreach on autopilot — with built-in daily limits and human-like pacing that protect your domain and reputation.
Start free in Flow AISales subject lines that move a deal forward
A sales subject line usually lands with a prospect who already knows you exist — a warm lead, a demo no-show, or a contact gone quiet mid-cycle. Here the job isn't to introduce yourself, it's to give a reason to re-engage without sounding like you're chasing a quota.
Tie the line to value or next steps, not to your forecast. Subject lines such as "next steps after our call", "the pricing breakdown you asked for" or "worth a 15-min recap?" perform because they reference something concrete the buyer cares about. Reference outcomes and mutual context; avoid "checking in" and "just following up", which signal nothing new is inside.
- Anchor to a deliverable, meeting or decision already in progress.
- Make the value obvious before they even open the email.
- Drop discount-bait and "free" words that trip spam filters and cheapen the offer.
Better subject lines in seconds
The subject line decides whether your email gets opened or ignored. Get it right.
2Generate & tweak
Add what it's about and get a set of options, each scored for length and deliverability. Copy your favourite.
3Test your own
Paste any subject line to grade it instantly — length, word count, spam triggers, caps and punctuation.
What makes a subject line work
Short & mobile-first
Most inboxes cut off around 50–60 characters. Lead with the part that earns the open.
Specific, not salesy
Spam-trigger words and ALL-CAPS hurt both opens and deliverability. The tester flags them for you.
Curiosity + relevance
The best lines hint at something useful and specific to the reader, without giving everything away.
Frequently asked questions
Win the open. Then let Flow AI win the reply.
No credit card required