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?
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.