Email Infrastructure Engineering
Practical implementation and operational guidance with validation, failure modes and rollback controls.
Authenticated Sender Authorization
Prevent SMTP users from submitting arbitrary MAIL FROM identities by mapping credentials to approved sender domains.
PowerMTA Listener Hardening
Separate submission and internal listeners, restrict source networks and reduce unauthenticated exposure.
Provider Policy Design
Create maintainable provider policies without fragile duplication or unsafe universal limits.
Queue Recovery Runbook
Recover from delivery slowdowns while preserving evidence and protecting critical traffic.
Microsoft Delivery Operations
Operate Microsoft-bound traffic using measured rates, SNDS evidence, complaint signals and careful recovery.
Gmail Delivery Operations
Manage Gmail-bound traffic with authentication alignment, recipient quality and Postmaster Tools evidence.
Yahoo and AOL Delivery Operations
Handle Yahoo/AOL deferrals, complaints and sender reputation using provider-specific controls.
GMX and WEB.DE Delivery Operations
Tune traffic conservatively and diagnose temporary failures for German mailbox providers.
Apple iCloud Delivery Operations
Plan identity, complaint handling and conservative delivery controls for Apple destinations.
Multi-Tenant Sending Boundaries
Isolate credentials, sender identities, queues, IP pools, logs and suppression data per customer.
MailWizz and PowerMTA Architecture
Design submission, bounce, feedback-loop and tenant routing boundaries for MailWizz deployments.
Postfix to PowerMTA Relay Design
Use Postfix as a local submission layer while preserving attribution and explicit routing into PowerMTA.
DKIM Delegation with CNAME
Delegate customer DKIM selectors to centrally managed keys while keeping DNS ownership clear.
Return-Path and Bounce Domain Design
Separate bounce identity, processing and alignment from the visible From address.
Feedback Loop Operations
Register, ingest, map and suppress complaint feedback without losing tenant attribution.
Accounting Log Processing Pipeline
Build a durable pipeline for delivery, bounce, deferral and queue event analytics.
Disk and Queue Capacity Planning
Estimate storage, headroom and recovery requirements from intake, delivery and message-size data.
DNS Resolver Design for MTAs
Deploy reliable recursive DNS with caching, observability, source selection and failure handling.
TLS Certificate Operations
Issue, deploy, renew and monitor SMTP certificates without accidental listener outages.
SMTP Credential Lifecycle
Create, scope, rotate, revoke and audit SMTP credentials for customers and applications.
MTA Change Control
Use checksums, peer review, staged rollout, monitoring gates and rollback for configuration changes.
Warm-Up Stop Conditions
Define measurable conditions that pause or roll back volume increases before reputation damage grows.
Suppression Governance
Protect recipients and reputation with durable hard-bounce, complaint and unsubscribe suppression.
Incident Evidence Collection
Collect queue, logs, DNS, provider responses and configuration state before making disruptive changes.