Scored email subject packs for A/B
Methodology: score · optional AI · human A/B
SubjectLab turns a pasted campaign brief into scored email subject-line variants with length and spam-risk flags so marketers can A/B without guessing in a blank ESP field.
1. What the engine owns
Variant generation, character counts, length_warn / multi_bang / spam-ish phrase flags, and ranking are deterministic heuristics. Demo is labelled Rule-based.
2. What optional AI may do
Polish subject wording when a key is configured. Upstream failure returns 502 — never a silent fake live pack. Scores remain heuristics, not open-rate predictions.
3. What you must do
- Resolve spam flags before send.
- A/B 2–3 winners in your ESP (ConvertKit, Loops, etc.).
- Do not treat scores as inbox or open-rate guarantees.
4. What we deliberately do not do
- Send email or warm domains.
- Native ESP OAuth in MVP.
- Promise deliverability or CAN-SPAM legal compliance.