Pick the right subject line in 30 seconds
Most guides hand you 100 examples and leave the 'which one fits this email?' problem on your desk. This is a decision tree — prospect state and body format map to the right pattern.
30s
to pick a subject
5
prospect states
2
body formats
Answer two questions, get the right pattern
Where is the prospect in the funnel? What's in the email body? Two answers map to a pattern with examples.
Question 1
What's the prospect's state?
- Cold — zero prior contact
- Warm — you've talked, no purchase
- Post-demo — just took a demo
- Dormant — no reply in 30+ days
Question 2
What's in the email body?
- Text only
- 1:1 personalized video
Five branches of the tree
One pattern per prospect state — plus the format-driven branch for video-body emails.
Zero prior contact
Pattern
Specific noun + curiosity gap
- {{firstName}}, your trial-to-paid leak
- Question on {{Company}}'s onboarding email #2
- 3 things {{Company}}'s pricing page is missing
- {{firstName}}, saw the Series B — quick thought
Beats 'Quick question' because the specificity proves it isn't a mass blast.
You've talked, no purchase
Pattern
Thread + new information
- Re: {{previous subject}}
- One more thing on {{Company}}'s {{topic}}
- {{Competitor}} just shipped this — your move?
- {{firstName}}, different angle on {{Company}}
After 3+ follow-ups in the same thread, start a new subject — the thread is dead.
Just took a demo
Pattern
Recap + decision question
- {{firstName}}, the 3 things from our demo
- Pricing options for {{Company}}
- {{firstName}} — what's blocking the call?
- The redlines you mentioned
Avoid 'Thanks for the demo!' — generic, no decision asked.
No reply in 30+ days
Pattern
Change-acknowledgment + low-pressure ask
- {{firstName}}, has anything changed at {{Company}}?
- {{Company}} 6 months later — different now?
- Was timing the only issue?
- {{firstName}}, surfacing this back up
After the third re-engagement with no response, mark closed-lost. Subject lines won't fix fit.
Email contains a 1:1 video
Pattern
Promise-the-video
- 90-sec video for {{firstName}}
- {{firstName}}, made you a 60-sec walkthrough
- Video: 3 things I'd change on {{Company}}'s site
- 2-min teardown video — {{Company}}
Wastes the video's curiosity advantage if the subject says 'Quick question' instead.
Template tools vs Outvid by scenario
Different sales motions need different subject-line tooling. Outvid's lane: outbound that needs to feel 1:1 at scale.
Cold outbound at scale
- Template toolsManual variables, generic patterns
- OutvidAI subject + 1:1 video per recipient
Post-demo follow-up
- Template toolsThank-you template
- OutvidThread + personalized video recap
Re-engagement
- Template toolsGeneric check-in
- OutvidSequences with branch logic on reply signal
Best for
- Template toolsQuick mail-merge sends
- OutvidOutbound that needs to feel 1:1 at scale
5 mistakes that kill open rates
Even a perfect pattern fails when the subject hits one of these. They're easy to miss because each one is invisible to the sender.
Too long
~41% of email opens are on mobile (Litmus). Previews truncate around 35–40 characters. Stay at 5–7 words.
Spam triggers
'Free,' 'guarantee,' 'act now,' '$$,' multiple exclamation marks. Skip them entirely — the open never happens.
All-caps + punctuation
Any word longer than 3 letters in caps + multiple `!` reads as spam to filters and humans alike.
Vague nouns
'Following up,' 'Quick question,' 'Touching base' are invisible. Replace with a specific company/page/metric.
Body mismatch
If the subject promises a video, the body must open with the video. 'Re:' must continue a real thread. Mismatch = deleted.
Common questions
What's the best subject line for a B2B sales email?+
The one that names something only their company would have — a specific page, metric, competitor, or recent event. Generic subject lines like 'Quick question' lose to 'your trial-to-paid leak' every time.
How is a sales email subject line different from a marketing email subject line?+
Sales subject lines optimize for 1:1 reply rate; marketing subject lines optimize for 1:many click-through rate. Sales subjects are short, specific to one recipient, and threaded into follow-ups. Marketing subjects can be cleverer because the audience is broader and forgives more.
Should sales email subject lines be personalized or generic?+
Personalized — but past the first name. '{{firstName}}' alone is now so common it reads as automated. Personalize with a specific noun from the recipient's company (a page, a metric, a recent event).
How many subject line variations should I test?+
Two at a time, minimum 50 sends per variant before calling a winner, and require ≥20% lift to scale. Three-variant tests need 3× the sample size for the same confidence — stick to two.
What length works best for sales email subject lines?+
5–7 words. This fits in the mobile-preview window where most opens happen and forces a discipline of specificity — long subject lines hide vague writing.
Skip the decision tree — let AI write the subject and the video
Drop in a prospect URL. Outvid picks the pattern, writes the subject line, and generates a matching 1:1 personalized video — all in seconds.