Case A — Acme Growth Agency (B2B marketing)
Actions taken (technical): Corrected SPF includes, enabled tenant DKIM with two selectors, published a DMARC record in monitor mode, removed legacy forwarding PTR records, implemented staged warm‑up on new sending subdomain, and applied header canonicalization to reduce suspicious tokens.
Measured outcome: Inbox placement tests (Gmail + Outlook) improved from 62% → 97% within 10 days. Reply rate from cold lists rose from 8% → 28% in the first two weeks (instant uplift +20pp). Over the following 6 weeks of monitored sends and engagement‑based warm‑ups, average reply rate stabilized at 40% (net +32% vs baseline).