A subject-line test that moved reply rate 7 points

A subject-line test that moved reply rate 7 points

A B2B consultancy A/B tested two subject styles across 600 prospects, 300 each, via Instantly's split feature. Same body, same sender.

— Version A (curiosity): "quick question about {company}" → 31% open, 4% reply
— Version B (specific): "{company}'s onboarding flow" → 44% open, 11% reply

Specificity beat curiosity by 7 reply points. The named-process subject signaled research, not a blast.

Pros of testing in-tool
— No spreadsheet stitching
— Auto-routes winner to remaining list
Cons
— Needs 200+ per arm for signal
— Open rates unreliable post-Apple MPP, lean on replies

Verdict: 4.5/5 on the method. The lesson isn't the tool — it's that vague-curiosity subjects underperform named-specifics at small scale.

Who it's for: anyone with 500+ comparable prospects. Skip A/B under 150 per arm — noise eats the result.