Email Security Blog
Practical guides on SPF, DKIM, DMARC, deliverability, blacklists, and protecting your domain from spoofing and phishing.
BIMI Requirements: VMC vs CMC
BIMI requirements explained: DMARC enforcement, SVG logo rules, VMC vs CMC certificates, which inboxes show your logo, and whether it is worth it.
Google and Yahoo Bulk Sender Rules
Google and Yahoo bulk sender requirements explained: SPF, DKIM, DMARC, one-click unsubscribe, spam-rate limits, Microsoft's rules, and how to verify each one.
How to Read Email Headers
Learn how to read email headers: find the full header in Gmail, Outlook, Apple Mail and Yahoo, then decode Received, SPF/DKIM/DMARC results and spot spoofing.
SPF Record Syntax: Complete Guide
A complete SPF record syntax reference: the version tag, every mechanism, qualifiers, redirect and exp, evaluation order, macros, length limits and common errors.
Best DMARC Monitoring Tools in 2026
Best DMARC monitoring tools in 2026, compared: free DMARC monitoring options, paid platforms, and self-hosted parsedmarc. Who each suits and what to check first.
BIMI Setup Guide for Gmail
BIMI setup guide: the DMARC, SVG and certificate steps, the exact DNS record, and how to test it so your logo shows next to email in Gmail and other inboxes.
DKIM Signature Failed: How to Fix It
dkim=fail, body hash did not verify, no key for signature: what each DKIM failure means, with real header examples, causes and fixes for Google and Microsoft 365.
DMARC Aggregate Reports Explained
How to read a DMARC XML aggregate report, element by element, with a sample report and fixes for each finding. Plus how to choose a DMARC report analyzer.
How to Warm Up a New Email Domain
Email domain warm-up explained: a sample 6-week volume schedule, who to send to first, and how to monitor with Google Postmaster Tools and Microsoft SNDS.
Google Workspace vs Microsoft 365 Security
Google Workspace vs Microsoft 365 email security compared: SPF, DKIM, DMARC defaults, anti-phishing tiers, MTA-STS, reporting, and what you must set up.
PowerDMARC Alternatives Compared
Looking for a PowerDMARC alternative? A fair comparison of PowerDMARC, dmarcian, EasyDMARC, Postmark, Cloudflare and parsedmarc, and when each fits.
Shopify Email Authentication Setup
Set up Shopify email authentication the current way: CNAME records for SPF and DKIM, a DMARC record, plus how Klaviyo, Mailchimp, and Google Workspace fit in.
SPF Hard Fail vs Soft Fail
SPF -all vs ~all: what hard fail and soft fail do, how DMARC changes the decision, and which to publish. Includes a decision guide and rollout steps.
SPF Too Many DNS Lookups: How to Fix
SPF permerror from too many DNS lookups breaks authentication for all your mail. See how lookups are counted, a worked example, and how to fix the 10-lookup limit.
Add Third-Party Senders to Your SPF Record
How to add Mailchimp, HubSpot, Salesforce and other third-party senders to SPF, plus the DKIM alignment step most guides skip and the subdomain approach.
The Real Cost of Email Spoofing
What email spoofing really costs a business: direct fraud losses, downtime, reputation and response time, with FBI IC3 figures and a worksheet to estimate yours.
DMARC p=none vs Quarantine vs Reject
DMARC p=none vs p=quarantine vs p=reject explained: what each policy does to mail, how to use pct to stage the rollout, and when it is safe to enforce.
Email Authentication for Microsoft 365
Set up SPF, DKIM, and DMARC for Microsoft 365: the exact SPF include, DKIM CNAME records, Defender portal steps, a DMARC record, and how to verify each one.
Email Deliverability Checklist
An ordered email deliverability checklist: DNS, authentication, reputation, list and content checks, each with how to verify it and which tool to use.
Google Workspace Migration Checklist
Migrating to Google Workspace? A step-by-step checklist covering TTL lowering, the MX cutover, SPF, DKIM, DMARC, MTA-STS, rollback, and the pitfalls that break mail.
How to Check an Email Blacklist
How to check an email blacklist: how DNSBL lookups work, how to read blacklist-checker results, and how Spamhaus, Barracuda and other delisting works.
DMARC Setup for Google Workspace
Set up DMARC for Google Workspace step by step: Admin console paths for SPF and DKIM, the exact DNS record, and a staged p=none to reject timeline.
MXToolbox Alternatives Compared
Looking for an MXToolbox alternative? Compare free SPF, DKIM, DMARC, and blacklist checkers, including where MXToolbox is still the better choice.
SPF, DKIM, and DMARC Explained
SPF, DKIM and DMARC explained in plain English: what each does, how they work together, a step-by-step flow, and how to set up and check all three.
What Is Business Email Compromise?
What is business email compromise? How BEC attacks work, why small businesses are targeted, FBI IC3 loss figures, and the controls that stop each type.
Why Your Emails Go to Spam
Why are my emails going to spam? Read the authentication results in a message header, match the error to its cause, and fix it in the right order.