Gmail verifies the sender, not the desire to receive those emails
Gmail's program for U.S. political committees does not promise the inbox. It formalizes a known rule: identity opens the door, reputation decides what follows.
SPF
Sender Policy Framework records, include mechanisms, and lookup limits.
17 articles
August 2026
June 2026
Hornetsecurity Secure Email Gateway (ex-Vade): architecture, DNS configuration and alternatives
Hornetsecurity 365 Total Protection is the cloud SEG for SMBs and MSPs (ex-Vade, now Proofpoint). Complete guide: architecture, mx01.hornetsecurity.com MX, spf.hornetsecurity.com SPF include, DKIM by CNAME, gateway vs API and a comparison with Proofpoint/Barracuda/Mimecast.
Barracuda Email Gateway Defense: architecture, DNS configuration and alternatives
Barracuda Email Gateway Defense is the cloud SEG for SMBs and MSPs (200,000+ customers). Complete guide: architecture, *.ess.barracudanetworks.com MX, SPF/DKIM/DMARC, DNS detection, the distinction with the ESG appliance (CVE-2023-2868) and a comparison with Mimecast/Proofpoint/Defender.
April 2026
Cloudflare Email Service: Email Routing, Security, and DMARC Management explained
Cloudflare now covers 4 email layers: free Email Routing, transactional Email Service (public beta April 2026), anti-phishing Email Security (formerly Area 1), and DMARC Management. Complete guide covering architecture, DNS, Proofpoint/Mimecast comparison, and pricing.
Cisco Secure Email Cloud Gateway (CES): SaaS architecture, iphmx.com DNS and ESA migration
Cisco Secure Email Cloud Gateway (CES) is Cisco's primary SaaS offering in 2026, the successor to the legacy ESA appliances inherited from Ironport. Complete guide: CES onboarding, iphmx.com MX records by region (NA/EU/APJ), SPF/DKIM/DMARC, migration from ESA to CES, 2024-2025 Gartner Magic Quadrant exit, zero-day CVE-2025-20393, comparison with Proofpoint, Mimecast, Defender and Abnormal.
Abnormal Security: behavioral AI, API deployment, and email gateway alternatives
Abnormal Security is an API-native ICES platform that detects BEC, VEC, and Account Takeover attacks using behavioral AI, with no MX change required. Complete guide: Attune 1.0 architecture, Proofpoint/Mimecast/Defender comparison, limitations, and DNS record audit.
Proofpoint Secure Email Gateway: architecture, DNS configuration and alternatives
Proofpoint is the enterprise SEG benchmark, used by 87 of the Fortune 100. Complete guide: Nexus AI architecture, TAP, SPF/DKIM/DMARC configuration, the 2024 EchoSpoofing incident and a comparison with Mimecast, Microsoft Defender and Abnormal Security.
Mimecast Secure Email Gateway: how it works, DNS setup, and alternatives
Mimecast is a cloud email gateway (SEG) that intercepts all traffic via MX redirection. Full guide: architecture, SPF/DKIM/DMARC setup, Proofpoint/Abnormal Security comparison, and DNS audit.
March 2026
Test Email Deliverability: The Complete Guide Before Sending
One in five emails never reaches the inbox. This guide shows you how to test your email deliverability before sending and fix every issue.
January 2026
Postmark (ActiveCampaign): Complete Technical Guide to Transactional Email
Detailed technical guide for developers: DNS configuration (DKIM, custom Return-Path), REST API vs SMTP, Message Streams, dedicated IP, webhooks and 2026 pricing.
Mailgun: Complete Technical Guide for Transactional Email
A detailed technical guide for developers: DNS configuration (SPF, 2048-bit DKIM with autorotation), REST API vs SMTP, dedicated vs shared IP, limits and webhooks.
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.
December 2025
Connect CaptainDNS to ChatGPT via MCP: 3 widgets for DNS audits and deliverability
Add the CaptainDNS MCP server to ChatGPT and use 3 widgets to troubleshoot DMARC/DNS and analyze email headers without leaving the conversation.
October 2025
