What Is ARC (Authenticated Received Chain) and Why Email Forwarding Needs It
ARC allows email forwarders to preserve authentication results across hops. Learn how Authenticated Received Chain works, who supports it, and why it complements SRS rather than replacing it.
Top 10 DNSBL Providers Compared: Spamhaus, Barracuda, SpamCop, and More
A practical comparison of the most widely used DNS-based blocklists. Learn how Spamhaus, Barracuda, SpamCop, SURBL, and others work, what they list, and which ones are worth using.
Why Your Email Forwarder Breaks SPF (and How SRS Fixes It)
Email forwarding breaks SPF authentication by design. Here is why it happens, what SRS does to fix it, and why this matters for deliverability.
The Hidden Life of an Email: From Send to Inbox in 12 Steps
You click Send. The email arrives 3 seconds later. But between those two clicks, your message traveled through DNS lookups, SMTP handshakes, TLS negotiation, spam scanning, virus checks, and authentication verification. Here is the complete journey.
Google and Yahoo Email Requirements: What Changed and What You Need to Do
In 2024, Google and Yahoo enforced strict authentication and unsubscribe requirements for bulk senders. Here is what you need to comply.
DMARC Alignment Explained: Why Authentication Alone Is Not Enough
Passing SPF and DKIM is not enough for DMARC. Learn what identifier alignment means, the difference between relaxed and strict modes, and why forwarding breaks SPF alignment but preserves DKIM alignment.
How to Audit Your Email Infrastructure for Security Weaknesses
Your MX records are public. Your SMTP banner reveals your software. Your TLS config may be outdated. Here is a step-by-step security audit of your email infrastructure using free tools - and how to fix what you find.
Why We Built Relay: The Problem with Traditional MX Gateways
Traditional email gateways treat every address the same. Relay was designed from scratch with per-address control, SRS forwarding, and crowd-sourced reputation.
Email Encryption Explained: TLS vs PGP vs S/MIME
Three encryption technologies, three different problems solved. TLS encrypts the connection. PGP encrypts the message. S/MIME does both with certificates. Here is when you need which.
What Is an Email Header? A Beginner's Guide with Real Examples
You have seen "Show original" in Gmail but never clicked it. Here is what email headers are, what they reveal, and how to use them to verify a sender or diagnose a delivery problem - explained simply.
What Happens When You Click Unsubscribe: The Full Technical Story
List-Unsubscribe headers, one-click POST requests, tracking pixels, preference centers, and CAN-SPAM compliance - the surprisingly complex machinery behind the unsubscribe button.
Rspamd Spam Symbols Explained: What Your Spam Report Is Telling You
Rspamd symbols decoded - BAYES_SPAM, DMARC_POLICY_REJECT, ZERO_FONT and 12 more. What each one means, why it triggered, and how to act on it.
