Measured against May 2026 NPPES endpoint_pfile (tightened HISP filter):
- 92,592 institutional NPIs across 38,873 practice domains (76% single-provider)
- 19,072 consumer-webmail NPIs (ride trucking discipline)
- 242,441 Direct/HISP rows parked until DirectTrust.
Decisions: single Postfix + class hc transport (:2526), 2nd Listmonk instance
(listmonk-hc, own cap + own listmonk_hc DB), 10k/day institutional ceiling.
Today one global Listmonk cap + shared Postfix rotation pool governs all mail,
sized to protect consumer-ISP (Gmail/MS/Yahoo) reputation for trucking cold mail.
Healthcare practice-domain (institutional) mail has an independent deliverability
profile and should run hotter without endangering the warmed trucking IPs.
Plan: isolate two streams sharing one Postfix/Listmonk:
- carve hc-dedicated sending IPs (.107-.109) with their own PTR/SPF + warmup;
- a 2nd Postfix submission service (:2526) bound to the hc pool;
- a 2nd Listmonk instance (or SMTP server) with its own sliding-window cap;
- split the healthcare list into institutional (hot) vs consumer-webmail (rides
trucking discipline) vs DirectTrust (parked);
- free MX+SMTP verify the institutional list on a non-sending IP first.
Includes mermaid topology, separate hc warmup/cap schedule, validation (isolation/
identity/deliverability/cap proofs), and open decisions for sizing.
