A subject line has one job: tell the right person, honestly, why this email is worth opening now. AI is good at giving you options fast. You are better at knowing which one sounds like you.
What makes a subject line work
- Specific — “Your October report is ready” beats “News from us”.
- Honest — it matches what is inside. Clickbait wins one open and loses the reader.
- Short — most people read email on a phone, where long lines are cut off.
- From a name they know — the sender name is read before the subject.
Let AI give you options
In Campaigns›New Campaign, Write with AI turns one line about the email into a draft and three subject lines. Your merge tags, such as {name}, are kept in place. Devlo uses your own AI key, set in Settings›Email Sending under AI Content Generation.
Then let your readers decide
Give the campaign a second subject line and Devlo splits the list 50/50. The campaign report shows both side by side — sent, open rate and click rate — and marks the winner.
What to avoid
- ALL CAPS and rows of exclamation marks.
- Fake “Re:” or “Fwd:” — it breaks trust and our Anti-Spam Policy.
- Promises the email does not keep.
- Testing ten ideas at once — test one change, learn one thing.
Put it into practice
Devlo has these checks built in. Start free — no card needed.
