Pricing freshness
Useful pricing has an expiry date.
EmailCostEngine prioritizes provider-owned pricing pages, official help centers, billing documentation and official affiliate-program documentation.
S1
Source hierarchy
Official provider sources are preferred. Third-party summaries are not authoritative pricing inputs.
S2
Freshness
Current thresholds: fresh through 30 days, aging through 60 days, stale after 60 days.
S3
Dynamic pricing
If a reliable static tier cannot be verified, the engine returns dynamic_price_required instead of guessing.