47% of email recipients open an email based on the subject line alone. Your perfectly crafted message is worthless if nobody reads it.
Here are 50+ proven subject line formulas organized by purpose, with real examples you can adapt.
The Science of Great Subject Lines
- Keep it short — 6-10 words, under 50 characters
- Create curiosity — But don't be clickbait
- Be specific — Vague = ignored
- Personalize when possible — Names increase open rates 26%
- Front-load important words — Mobile truncates after ~35 chars
Cold Outreach Subject Lines
The Question Approach
Quick question about [Company]'s [initiative]
[Name], quick question
Curious about your approach to [topic]
The Mutual Connection
[Mutual contact] suggested I reach out
Fellow [group/school/company] alum
[Name] from [Event] — following up
The Value Proposition
Idea to help [Company] with [specific goal]
How [Similar Company] increased [metric] by [X]%
[Specific result] for [their industry] companies
Follow-Up Subject Lines
Re: [Original subject]
Following up on [topic]
Did you get a chance to review?
Bumping this to the top
One more thought on [topic]
Closing the loop on [topic]
Job Application Subject Lines
[Position] Application — [Your Name]
Excited about the [Position] role at [Company]
[Referral name] recommended I apply
[Position]: [Your unique angle in 3 words]
Following up: [Position] interview
Networking Subject Lines
Loved your talk at [Event]
Your [article/post] on [topic]
Coffee? (15 min, your convenience)
Fellow [profession] — would love to connect
[Mutual interest] enthusiast here
Generate Perfect Subject Lines
FlirtCopilot analyzes context and generates subject lines optimized for opens. Never stare at a blank subject field again.
Get the Free Chrome ExtensionMeeting Request Subject Lines
15 min to discuss [specific topic]?
Calendar hold: [Topic] sync
Can we chat about [project] this week?
[Name] ↔ [Your name]: [Topic]
Internal/Work Subject Lines
[Project] Update — [Status/Date]
Need input: [Specific decision]
FYI: [Brief summary]
Action needed by [Date]: [Topic]
Quick review request: [Document]
Subject Lines to AVOID
- "Hi" or "Hello" — Zero information, looks like spam
- ALL CAPS — Screams desperation
- "URGENT" (when it's not) — Crying wolf
- Clickbait — "You won't believe this!" destroys trust
- Too clever — Puns often confuse more than amuse
- 🚀💰🔥 Emoji overload — One emoji max, if any
Key Takeaways
- Under 50 characters (6-10 words)
- Be specific about the content
- Personalize with names or references
- Create curiosity without clickbait
- Front-load the important words
- Test different approaches