Email protocols, configuration, and best practices for reliable messaging.
20 articles
Configure MTA-STS for Microsoft 365 and Google Workspace
Step-by-step tutorial to deploy MTA-STS on Microsoft 365, Google Workspace, and Cloudflare. MX patterns, policy file, hosting, and validation included.
Spamhaus vs Barracuda vs SpamCop: Complete Email Blocklist Comparison
Detailed comparison of the 3 main email blocklists: detection methods, false positive rates, delisting procedures, and impact on Gmail, Outlook, and Yahoo deliverability.
Why Your Emails End Up in Spam: The Complete Diagnostic Guide
Are your emails consistently landing in spam? This guide analyzes the 5 main causes and gives you a concrete action plan to restore optimal deliverability.
How to Remove Your IP from a Blacklist: The Complete Delisting Guide
Is your IP on a blacklist and your emails getting rejected? This guide details the delisting procedures for each major blacklist, including processing times and best practices to avoid getting listed again.
Twilio SendGrid: Complete Technical Guide for Transactional Email
A detailed technical guide for developers: DNS configuration (SPF, 2048-bit DKIM), Web API v3, SMTP Relay, dedicated vs shared IP, limits and webhooks.
BIMI, VMC, CMC: compatibility and DNS prerequisites (Gmail, Yahoo, Apple Mail)
Putting your logo in the inbox: what you actually need to configure in DNS for BIMI, and how to choose between VMC and CMC.
Gmail/Yahoo one-click unsubscribe: what RFC 8058 changes and how to implement it
Gmail and Yahoo require a one-click unsubscribe via RFC 8058-compliant List-Unsubscribe headers. Here's the expected format, the server-side POST, and the compliance checklist.
Gmail ends POP fetching from other accounts in 2026: impact and action plan
Starting January 2026, Gmail will no longer continuously fetch messages from external mailboxes via POP ("Check mail from other accounts"). Impacts, timeline, and alternatives for Gmail and Google Workspace users and admins.
Behind the scenes of the CaptainDNS MCP
How we wired CaptainDNS to AIs through MCP: architecture, HTTP+SSE transport, JSON-RPC, 424 errors, timeouts, and what we learned along the way.
BIMI logo cache: run a brand refresh and make the new logo show up everywhere
Your logo changed but inboxes still display the old one? It is not only a DNS issue: mailbox providers cache BIMI assets. Discover how the cache layers work and how to plan a smooth BIMI migration.
Gmail tightens its sending rules: what's changing for senders starting November 2025
Starting in November 2025, Google enforces new security requirements for bulk senders: full SPF/DKIM/DMARC authentication, TLS encryption and strict unsubscribe management.
