The subject line is the only sentence that decides whether your email gets opened. A great one is short, specific and answers the reader’s silent question: what’s in this for me?
This is the quick version. For the full method and 10 examples, read how to write an effective email subject line. For the basics, see what an email subject line is.
Five things great subjects do
- Be specific, not clever — «Free shipping ends Friday» beats «Don’t miss out!»
- Front-load value — Put the offer or news in the first 30 characters
- Match the body — If you promise a guide, deliver a guide
- Sound human — Write like a colleague, not a press release
- Personalize when it adds info — First name only when it actually changes the message
Subject line length
Mobile clients clip subjects around 35–50 characters. Aim for that range and pair it with a strong preheader. More on length: subject line length.
Use emojis sparingly
One emoji can lift opens; three look like a flea market. See emoticons in newsletter subjects.
Test, then test again
A/B test two subjects on a small slice of the segment, send the winner to the rest. Over time, build your own playbook of formats that work for your audience. Background reading: how to create the ideal email subject and subject lines as title tags.
Need ideas?
Try Mailpro’s AI generator: email subject line generator. AI works best as a starting point you then refine. See AI email subject lines.
Open rate is decided in 50 characters
Lead with value, keep it specific, A/B test two variants, refine the winner. Stuck? Use the subject line generator for first drafts.
Related guide: Email preheader: what it is, ideal length and examples
12 email subject line examples you can adapt
- Promotion: "48 hours only: 20% off all shoes"
- Free shipping: "Free shipping ends Friday"
- Welcome: "Welcome to the club, here's your 10% code"
- Newsletter: "3 ideas to plan your spring menu"
- Product launch: "New: the lighter version you asked for"
- Event: "Your seat for Thursday's webinar is saved"
- Reminder: "Last chance: registration closes tonight"
- Abandoned cart: "You left something in your cart"
- Re-engagement: "We miss you, Laura. Still interested?"
- Feedback: "How was your order? (1-minute survey)"
- Content: "The checklist we use before every send"
- Personal: "Marc, your report for October is ready"
Test two versions of your subject on a small part of your list and send the winner to everyone else.
Mailpro and subject lines
Write subject lines that get opened
Draft subject line ideas in seconds with the Mailpro AI subject line generator, then A/B test them on your list. Swiss-hosted and GDPR-native.