Email Deliverability Guides
Plain-English explanations of SPF, DKIM, DMARC, and everything else that determines whether your emails land in the inbox or the spam folder.
What is an SPF Record?
SPF tells the internet which mail servers are allowed to send email from your domain — and what to do with everyone else.
What is DKIM?
DKIM adds a digital signature to every email you send, proving it came from you and wasn't tampered with in transit.
What is DMARC?
DMARC is the policy that tells receiving servers what to do when an email fails your SPF and DKIM checks.
What is an MX Record?
MX records tell the internet where to deliver email for your domain. Without them, email bounces immediately.
Email Blacklists Explained
Being listed on a spam blacklist can stop your emails from reaching inboxes entirely. Here's how they work and how to get off them.
What is BIMI?
BIMI lets your brand logo appear next to your emails in Gmail and Yahoo — making your emails instantly recognisable.
SPF vs DKIM vs DMARC: What's the Difference?
Three acronyms, three different jobs. Learn what each one does and why you need all three for proper email authentication.
Why Are My Emails Going to Spam?
Email landing in spam has specific, fixable causes. Diagnose and fix authentication failures, blacklist listings, and reputation problems.
Google Workspace: SPF, DKIM & DMARC Setup
Step-by-step guide to setting up email authentication for Google Workspace — including the exact DNS records to add.
Microsoft 365: SPF, DKIM & DMARC Setup
Step-by-step guide to setting up email authentication for Microsoft 365 — SPF record, DKIM CNAME records, and DMARC policy.
SendGrid: SPF, DKIM & DMARC Setup
How to authenticate your sending domain in SendGrid using Domain Authentication — the three CNAME records that handle SPF and DKIM.
SPF Too Many DNS Lookups: How to Fix It
Exceeding SPF's 10-lookup limit causes a permerror that breaks email delivery. Learn to diagnose it and fix it with SPF flattening.
Amazon SES: SPF, DKIM & DMARC Setup
Authenticate your sending domain in Amazon SES — including the custom MAIL FROM domain that most guides skip.
Mailchimp DKIM Setup: Fix "via mcsv.net" in Gmail
Domain authentication for Mailchimp removes the "via mcsv.net" label in Gmail and improves campaign deliverability.
DMARC Reports Explained: How to Read Them
DMARC aggregate reports show who is sending email as your domain. Learn what each field means and how to use reports to reach p=reject safely.
MxToolbox Alternative: EmailHealth
How EmailHealth compares to MxToolbox for email deliverability checking — one report covering all 7 authentication checks.
Gmail & Yahoo 2024: SPF, DKIM & DMARC Now Mandatory
Google and Yahoo now require authentication for all senders. Exactly what changed, who is affected, and how to comply before your emails get rejected.
Cold Email Deliverability: The Complete Setup Checklist
Cold email only works if it lands in the inbox. The exact SPF, DKIM, DMARC, domain, and infrastructure setup that separates inbox from spam.
Klaviyo: SPF, DKIM & DMARC Setup Guide
Set up a dedicated sending subdomain in Klaviyo, publish the required DNS records, and verify authentication in 20 minutes.
HubSpot: SPF, DKIM & DMARC Setup Guide
Connect a custom sending domain in HubSpot, publish SPF and DKIM records, and remove the "via hubspotemail.net" label from Gmail.
How to Fix DMARC Failure
DMARC failure means SPF and DKIM alignment both failed. Diagnose which type you have and follow the exact fix for each cause.
What is Email Deliverability?
The complete guide to email deliverability — authentication, reputation, content, and list hygiene. Every factor that determines inbox vs spam placement.
Email Warmup: How to Warm Up a New Domain or IP
A new domain has zero reputation. Warm it up gradually or Gmail and Outlook will route your email to spam before most of your list ever sees it.
Mail-Tester Alternative: EmailHealth vs Mail-Tester
DNS-based checking vs real-send spam testing — what the difference is and which tool to use for your specific problem.
EasyDMARC Alternative: EmailHealth vs EasyDMARC
When a free DNS checker is enough vs when you need a full DMARC report management platform. The honest comparison.
Mailchimp Emails Going to Spam? Here's Why
The specific causes of Mailchimp spam placement — domain authentication, shared IP reputation, list hygiene — and the fix for each.
SendGrid Deliverability Problems: Diagnose and Fix
SendGrid emails going to spam or bouncing? Authentication misalignment, shared IP reputation, bounce management — every common failure and its fix.
SMTP Error Codes: Complete Reference
Every 4xx and 5xx SMTP error code explained — standard codes plus Gmail, Outlook, and Yahoo-specific sub-codes, each with the fix.
Office 365 Emails Going to Spam? Here's Why
Microsoft EOP is aggressive — authentication failures, IP reputation, missing PTR records, and complaint rate each cause Junk folder placement. The fix for each.
Klaviyo Emails Going to Spam? Here's Why
Klaviyo campaigns landing in spam or Gmail Promotions? Domain authentication, list quality, engagement rate, and content — every cause and its fix.
HubSpot Emails Going to Spam? Here's Why
HubSpot marketing emails or sales sequences landing in Junk? Custom domain not connected, DMARC alignment failure, bounce rate — the specific cause and fix.
Top 5 Free Business Email Providers in 2026
The best free business email options that work with your own domain — Zoho Mail, Neo, Google Workspace, Proton Mail, and ImprovMX compared with honest free-tier details.
Best Transactional Email Services in 2026
SendGrid vs Mailgun vs Postmark vs Amazon SES vs Resend vs Brevo — compared on deliverability, pricing, developer experience, and what each is actually best for.
Best Email Warm-Up Tools in 2026
Lemwarm vs Mailreach vs Warmbox vs Instantly vs Smartlead — compared on network size, pricing, and whether standalone warm-up tools are still worth it.
Best DMARC Monitoring Tools in 2026
dmarcian vs Postmark vs Valimail vs EasyDMARC vs URIports — compared on report parsing, pricing, and what level of DMARC management you actually need.
Best Email Verification Services in 2026
ZeroBounce vs NeverBounce vs Kickbox vs Hunter vs Bouncer — compared on accuracy, pricing, real-time API support, and GDPR compliance.
Best Email Testing Tools in 2026
Litmus vs Email on Acid vs Mailtrap vs Mail-Tester vs Putsmail — compared on rendering previews, spam testing, developer sandboxes, and pricing.
Google Workspace vs Microsoft 365 for Business Email (2026)
Google Workspace vs Microsoft 365 compared on email deliverability, storage, pricing, apps, and authentication setup. Which is better for your business?
Zoho Mail vs Google Workspace: Which Is Better for Business?
Zoho Mail vs Google Workspace compared on free tier, pricing, deliverability, authentication setup, and apps. Which is the right choice for your business?
Best Cold Email Software in 2026
Instantly vs Lemlist vs Smartlead vs Apollo vs Woodpecker — compared on deliverability features, inbox rotation, pricing, and what actually gets replies.
Dmarcian Alternative: Free DMARC Checking
Dmarcian costs $199+/month. EmailHealth checks DMARC, SPF, DKIM, and blacklists for free with no account. Here's how the tools compare and when to use each.
Valimail Alternative: Free DMARC Checking
Valimail is enterprise DMARC enforcement. EmailHealth checks DMARC, SPF, and DKIM configuration for free in seconds — no sales call, no contract.
GlockApps Alternative: Free Email Deliverability Check
GlockApps tests inbox placement by sending emails. EmailHealth checks DNS configuration. Understanding the difference saves you time and money.
Google Workspace DKIM for Secondary Domains
Every domain in Google Workspace needs its own DKIM key. How to generate, publish and start it, and why Generate is greyed out.
EmailGuard Alternative: Daily Domain Monitoring for Cold Email
Weekly vs daily domain checks, alerts, fixes and price per domain. When EmailGuard is the better choice, and when EmailHealth is.
Mailgenius Alternative: Free DNS-Based Deliverability Check
Before testing spam scores, check if DNS configuration is causing your deliverability problems — free, instant, no account needed.
Folderly Alternative: Fix Deliverability Without Paying for Warmup
Folderly costs $49–99/month. Many deliverability problems are DNS configuration issues — fixable for free in minutes before you consider warmup.
Warmup Inbox Alternative: Check DNS Before You Warm Up
Warmup builds reputation, but it doesn't fix authentication failures or blacklist listings. Check your DNS configuration first — it's free.
InboxAlly Alternative: Diagnose Email Problems Free
InboxAlly builds engagement signals. But most deliverability problems are SPF, DKIM, DMARC, or blacklist issues — free to check and fix.
What is a PTR Record? Reverse DNS for Email Explained
PTR records are the reverse of A records — they map an IP address back to a hostname. Missing or mismatched PTR records are a common cause of email rejection.
DMARC none vs quarantine vs reject: Which Policy Should You Use?
The three DMARC policy levels do very different things. p=none monitors without protecting, quarantine sends failures to spam, reject blocks them outright.
Shopify Email: SPF, DKIM & DMARC Setup Guide
How to authenticate your Shopify store emails — transactional notifications, Shopify Email campaigns, and custom domain setup — with exact DNS records.
Email Sender Reputation: What It Is and How to Improve It
Sender reputation is how Gmail, Outlook, and Yahoo decide whether your email lands in the inbox or spam. Domain reputation, IP reputation, and engagement all feed into it.
Sender Score Alternative: Free Email Reputation Check
Sender Score measures IP reputation on a 0–100 scale. Here is how it fits into your deliverability toolkit — and what EmailHealth adds that Sender Score does not cover.
Postmark Spam Check Alternative: Free DNS-Based Deliverability Check
Postmark's spam check tests an actual email message for content triggers. EmailHealth checks your DNS configuration — the layer underneath that causes most delivery failures.
Free Inbox Placement Test: Does Your Email Land in the Inbox?
Most inbox placement testing tools charge money. This guide explains what inbox placement testing measures and how to run a complete free test — no account, no credit card.
What Is Inbox Placement? (And Why It's Different from Delivery Rate)
Your email can be delivered and still never be seen. Inbox placement is what actually determines whether your message reaches the inbox — and it's controlled by factors most senders never check.
Gmail Inbox Placement Test: What Gmail Checks Before It Lets Your Email In
Gmail is the world's most aggressive spam filter. Learn which signals it uses — DKIM alignment, 2024 bulk sender requirements, engagement history — and how to fix the most common failures.
Outlook Inbox Placement Test: Why Outlook Filters Differently from Gmail
Outlook uses SCL scores, Exchange Online Protection, and SNDS reputation data. Learn the Microsoft-specific signals that determine inbox placement and how to fix common Outlook failures.
Inbox Placement Rate: The Metric Your ESP Isn't Showing You
Delivery rate tells you how many emails were accepted. Inbox placement rate tells you how many reached the inbox. Learn what a good IPR looks like and how to improve it.
Email Deliverability Test: Everything You Need to Check Before You Send
A complete guide to email deliverability testing — DNS configuration checks vs header analysis, what each one catches, and how to run both for free before your next send.
Free Email Spam Test: Will Your Email Pass Spam Filters?
Run a free email spam test on a real message you send. Get your SpamAssassin score, DKIM/SPF/DMARC results, IP blacklist status, and the exact rules that are triggering spam filters.
How to Check If Your Email Is Going to Spam (And Fix It)
Signs your email is landing in spam, how to diagnose the cause using headers and DNS, and how to fix every common spam placement problem — DKIM, SPF, IP blacklists, and content.
Yahoo Mail Inbox Placement Test: What Yahoo Checks Before Delivering Your Email
Yahoo Mail applies strict filtering — especially since joining Google's 2024 bulk sender requirements. Learn Yahoo-specific signals, the Complaint Feedback Loop, and common delivery failures.
SendGrid Inbox Placement Test: Why SendGrid Emails Go to Spam and How to Fix It
SendGrid's default config leaves DMARC alignment broken and shared IPs unchecked. Learn how to test and fix SendGrid inbox placement — Domain Authentication, IP reputation, and more.
Mailchimp Inbox Placement Test: Why Campaigns Go to Spam or Promotions
The "via mcsv.net" label and DMARC alignment failures are the two most common Mailchimp inbox placement problems. Here's how to diagnose and fix both.
Inbox Placement Test for Cold Email: The Setup Checklist That Actually Matters
Cold email has zero tolerance for spam folder placement. Test your sending domain's authentication, IP reputation, and SpamAssassin score before your first outreach sequence.
Mailgun: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through Mailgun, with provider-specific gotchas.
Postmark: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through Postmark, with provider-specific gotchas.
Brevo (Sendinblue): SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through Brevo (Sendinblue), with provider-specific gotchas.
Mailjet: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through Mailjet, with provider-specific gotchas.
SMTP2GO: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through SMTP2GO, with provider-specific gotchas.
SparkPost: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through SparkPost, with provider-specific gotchas.
Mandrill (Mailchimp Transactional): SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through Mandrill (Mailchimp Transactional), with provider-specific gotchas.
Zoho Mail: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through Zoho Mail, with provider-specific gotchas.
MailerSend: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through MailerSend, with provider-specific gotchas.
Elastic Email: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through Elastic Email, with provider-specific gotchas.
Resend: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through Resend, with provider-specific gotchas.
ActiveCampaign: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through ActiveCampaign, with provider-specific gotchas.
Constant Contact: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through Constant Contact, with provider-specific gotchas.
GetResponse: SPF, DKIM & DMARC Setup
The exact DNS records to authenticate email sent through GetResponse, with provider-specific gotchas.