What Is a Mail Relay and How Does It Work
A beginner-friendly explanation of mail relays - what they are, why they exist, how they fit into the SMTP chain, and the different types of relays used in modern email infrastructure. Understand the technology that sits between the internet and your mailbox.
How Cleanbox Filters Work Under the Hood
A deep dive into the filter engine: 10 condition types, 12 operators, rule groups with boolean logic, and how filters interact with contact states and spam scoring.
What Is TLS in Email and How Does It Protect Your Messages
TLS is the encryption standard that protects your emails in transit. Learn how TLS works in email, what STARTTLS does, the difference between opportunistic and enforced TLS, and what TLS does not protect.
Passkeys Explained: What They Mean for Email Security
Passkeys promise a future without passwords - no more phishing, no more credential stuffing, no more password reuse. But even in a passkey world, email remains the critical weak point. Here is why email security matters more than ever.
Email Authentication in Practice: When SPF, DKIM, and DMARC Pass and When They Fail
You know what SPF, DKIM, and DMARC are. But do you know why forwarded email fails SPF? Why mailing lists break DKIM? Why DMARC can reject legitimate email? Real-world scenarios explained.
How to Show Your Logo Next to Emails in Gmail (BIMI Explained)
BIMI displays your brand logo next to emails in Gmail, Apple Mail, and Yahoo. Here is what it requires and two ways to set it up.
How Spamhaus Detects Spammers: Inside the World's Largest Threat Intelligence Network
Spamhaus is the most influential anti-spam organization on the planet. Their blocklists protect billions of mailboxes and their decisions can cut off entire networks from email delivery. Here is how they actually work, from spam traps to legal battles.
What Happens to Your Email Before It Reaches Your Inbox?
From the moment someone clicks send to the moment it lands in your inbox - the surprisingly complex journey of an email through DNS, SMTP, spam filters, and authentication.
One-Click Unsubscribe - How It Works and Why Not Every Email Has It
Ever wonder why some emails show an unsubscribe button at the top and others do not? Learn how one-click unsubscribe works technically, why Google and Yahoo now require it, and when it is safe to use.
How We Built Contact Categorization (and Why It Changes Filtering)
Every sender is automatically sorted into one of 20 categories based on their domain. This is not just organization - it unlocks category-based filtering that works on emails you have never seen before.
The Complete Guide to Email Deliverability for Small Senders
You send fewer than 5,000 emails a day but messages still land in spam. A practical guide to authentication, reputation, and content for small-volume senders.
How Gmail Detects Spam: An Inside Look at Google's Email Filtering
Gmail processes billions of emails daily with a multi-layered spam detection system. Here is how authentication checks, reputation scoring, machine learning, and user signals work together to filter spam.
