Eleven published deliverability heuristics scored transparently: mobile truncation length, spam-trigger phrases, shouting, punctuation, merge tokens, numeric specificity, curiosity framing, urgency, emoji, and preview-text fit. No LLM — the arithmetic is exposed so a marketer can argue with any single rule and get the same score twice.
Mobile inbox preview
Mashdun
Your Q3 report is ready — 3 things stood out
The churn number moved for a reason worth 5 minutes of your time.
Score
70/100
Length
44 chars — survives mobile truncation (~45).
Word count
10 words — 4–9 scans best in a crowded inbox.
Spam triggers
No common filter-bait phrases.
Capitalization
Normal sentence casing.
Punctuation
No exclamation marks.
Personalization
No merge token. Consider a first name or company.
Specificity
Contains a number — concrete beats vague.
Curiosity
Statement only. A question often out-opens a claim.
Preview text
65 chars — complements the subject in the preview pane.
A model asked to 'predict open rate' will hand you a confident number it can't defend. These are published deliverability heuristics with the arithmetic exposed, so a marketer can argue with any single line of it — and get the same score twice. That auditability is the point; the same principle governs the scoring in our valuation and lead-scoring work.
