Backscatter: The Bounces You Never Sent
When spammers forge your domain as their envelope sender, the bounces come to you. What backscatter is, why it happens, and how to stop causing and receiving it.
Infrastructure
Understand the infrastructure behind global communication networks, including telecom architecture, messaging APIs, routing systems, push notification services, CPaaS platforms, cloud communication systems, and real-time messaging technologies.
DNSSEC for Email Operators: Worth It, and How Not to Break Everything
Every email trust decision resolves through DNS, and DNSSEC is what makes those answers tamper-proof. What it buys email, what DANE requires, and safe operations.
Transactional Latency: Measuring Time-to-Inbox
For OTPs and password resets, seconds are the metric. Where latency hides in the sending path, how to measure time-to-inbox honestly, and what budgets to hold.
Bot Clicks and Link Scanners: Cleaning Your Click Data
Security gateways click every link in every email before humans see them. How scanner traffic pollutes click metrics, breaks one-click flows, and how to filter it.
Greylisting, Tarpitting, and Other Receiver Defenses Senders Should Understand
Receiving servers defend themselves with deliberate delays, temporary rejections, and traps for impatient senders. How each defense works and how a good MTA passes them.
Building a Deliverability Monitoring Stack
Postmaster Tools, SNDS, FBLs, DMARC reports, TLS-RPT, bounce logs, engagement data: the full observability stack, what each layer catches, and the alerts worth paging on.
Duplicate Sends: Idempotency in Email Pipelines
Everyone has received the same email twice. The retry loops, queue semantics, and race conditions that cause duplicates, and the idempotency patterns that stop them.
DNS for Email: The Records, TTLs, and Chains That Break Mail
Email is a DNS application. The full record inventory a sending domain needs, the TTL strategy for safe changes, and the misconfigurations that quietly break delivery.
SMTP Relay vs. API Sending: Architecture Trade-offs That Matter
Every sending platform offers SMTP relay and an HTTP API. The differences in latency, error handling, portability, and observability, and how to choose per workload.
Email Header Forensics: Reading Received Chains and Authentication-Results
Every delivery question has its answer in the headers. How to trace a message's path through Received lines and decode Authentication-Results like a postmaster.
Migrating ESPs Without Destroying Your Sender Reputation
Switching email providers resets your IPs, your DKIM keys, and every provider assumption about your traffic. A migration plan that carries your reputation across.
MTA-STS in Practice: Adoption, Tooling, and Real Implementation
MTA-STS closes the STARTTLS downgrade hole by letting domains require verified TLS for inbound mail. The policy file, the DNS record, and the gotchas in between.
Feedback Loops: Setting Up JMRP, Yahoo CFL, and a Complaint Data Pipeline
Feedback loops send you the complaints your recipients file. How to register with Microsoft, Yahoo, and the rest, and what to build so the data actually gets used.
Bounce Classification: Hard, Soft, and What Your Handling Logic Gets Wrong
Hard versus soft is not enough. How SMTP codes, enhanced status codes, and provider quirks should drive your retry, suppression, and reputation logic.
Postmaster Tools vs. SNDS: Reading Gmail and Microsoft Reputation Data
Gmail Postmaster Tools and Microsoft SNDS report sender reputation in fundamentally different ways. How to read both dashboards and act on what they actually show.
Why DMARC Alignment Matters More Than DMARC Itself
DMARC fails when SPF or DKIM pass for the wrong domain. The alignment rules, relaxed vs strict modes, and the ESP configuration that fixes it.
One-Click Unsubscribe (RFC 8058): Implementation Pitfalls Most Senders Miss
RFC 8058 one-click unsubscribe is mandatory for bulk senders. The five implementation mistakes that fail compliance and how to test your endpoint properly.
The ARC Header: How Forwarding Breaks DMARC and What You Can Do
Forwarders break DMARC by modifying messages in transit. ARC (RFC 8617) preserves authentication results across hops. How it works, who supports it, and the limits.
Why Your Transactional Emails Are Landing in Spam (And Mixing Them with Marketing Is The Reason)
Password resets going to spam? You're sending them from the same IP and domain as marketing campaigns. The four operational fixes that actually work.
IP Warming in 2023: A 30-Day Schedule That Actually Works
Most IP warming schedules fail because they ignore engagement segmentation. The 30-day ramp that actually works volume tables, segment ordering, and recovery rules.