SMTP Codes: What They Are and How to Troubleshoot Them
Learn what SMTP codes mean, how to separate temporary from permanent failures, and troubleshoot delivery, DNS, TLS, and reputation issues.
Aug 13, 202625 min read
Dns
80 articles on dns.
Resolving AWS Port 25 Throttling: A Practical Guide
Resolve AWS Port 25 throttling with proven SMTP tests, alternate ports, removal-request guidance, DNS checks, and reliable email architecture.
Aug 13, 202621 min read
Domain Not Verifying? A Developer’s DNS Troubleshooting Guide
Domain not verifying? Diagnose TXT, CNAME, SPF, DKIM, and DNS propagation errors with practical commands and fixes for email sending domains.
Aug 12, 202618 min read
What If an Email Says Delivered but the Recipient Has Not Received It?
Learn why an email says delivered but is not received, how SMTP delivery works, and the DNS, header, and inbox checks that pinpoint the issue.
Aug 12, 202621 min read
Is It Better to Send Emails From a Subdomain or Root Domain?
Should you send emails from a subdomain or root domain? Learn the deliverability, DNS, DMARC, reputation, and operational trade-offs.
Aug 12, 202622 min read
Apple Branded Mail Setup: DNS, DMARC, and Verification Guide
Set up Apple Branded Mail with the right DMARC policy, DNS verification, brand assets, testing workflow, and troubleshooting steps.
Aug 12, 202622 min read
MX Record Conflicts: Avoid Breaking Your Email Flow
Avoid MX record conflicts without disrupting inbound mail, transactional sending, SPF, DKIM, DMARC, replies, or bounce handling.
Aug 11, 202623 min read
2048-bit DKIM: Do You Need It for Email Delivery?
Do you need 2048-bit DKIM? Learn when 1024-bit is acceptable, how DNS limits affect setup, and how to verify DKIM for reliable delivery.
Aug 11, 202619 min read
Email Setup for New Domains: The Launch Task Founders Keep Underestimating
Email setup for new domains is a hidden launch tax. Learn how to standardize routing, sending, DNS authentication, and replies at scale.
Aug 10, 202620 min read
Email Authentication Error: Fix SPF, DKIM, and DMARC Failures
Fix an email authentication error with a practical SPF, DKIM, and DMARC checklist, DNS record examples, header checks, and troubleshooting steps.
Aug 7, 202620 min read
DMARC Record Format: Syntax, Tags, Examples, and Setup
Learn the DMARC record format, required syntax, every important tag, rollout steps, troubleshooting tips, and copy-ready DNS examples.
Aug 5, 202617 min read
DMARC Record Published: How to Add, Verify, and Enforce It
A DMARC record published correctly is only the start. Learn exact DNS TXT syntax, testing steps, alignment checks, and a safe enforcement rollout.
Aug 5, 202618 min read
Free SMTP Relay: Send Transactional Email Without Running a Mail Server
Set up a free SMTP relay for transactional email: compare quotas, configure DNS authentication, send a secure test, and troubleshoot delivery.
Aug 4, 202620 min read
DMARC Record Entry: Exact Syntax, DNS Setup, and Examples
Learn the exact DMARC record entry syntax, DNS host name, policy tags, reporting setup, testing steps, and a safe rollout example for any domain.
Aug 2, 202619 min read
Email Authentication Settings: Configure SPF, DKIM, and DMARC Correctly
Set email authentication settings correctly with SPF, DKIM, and DMARC. Use DNS record examples, tests, and fixes to protect delivery.
Aug 2, 202621 min read
DMARC Record Example: Copy, Configure, Test, and Enforce
Use this DMARC record example to publish the right DNS TXT record, monitor SPF and DKIM alignment, fix failures, and safely reach p=reject.
Aug 1, 202618 min read
DMARC Record Lookup: Check, Read, and Fix Your DNS Policy
Run a DMARC record lookup, interpret every important tag, diagnose missing or invalid DNS records, and verify your email domain is protected.
Aug 1, 202622 min read
DMARC Record Check: How to Validate, Fix, and Test Your DNS Policy
Run a DMARC record check, read the DNS result, fix common syntax and alignment errors, and verify your email policy works before enforcing it.
Aug 1, 202617 min read
DMARC Record Error Detected: How to Find and Fix It
Fix a DMARC record error detected warning with exact DNS syntax, alignment checks, testing commands, common mistakes, and a worked example.
Aug 1, 202618 min read
DMARC Record for Microsoft 365: Setup, Syntax, and Testing
Create a DMARC record for Microsoft 365 with correct SPF and DKIM alignment, a safe rollout plan, reporting, troubleshooting, and testing steps.
Jul 31, 202619 min read
DMARC Record Checker: Check, Interpret, and Fix Your DMARC Record
Use a DMARC record checker to find, validate, interpret, and fix your DNS policy. Includes syntax, alignment tests, errors, and a worked example.
Jul 28, 202617 min read
DMARC Record Creator: Build, Publish, and Validate Your DMARC Policy
Use this DMARC record creator guide to build correct DNS syntax, collect reports, move safely to enforcement, and validate your email authentication.
Jul 28, 202619 min read
DMARC Records O365: Set Up Microsoft 365 Without Breaking Mail
Set up DMARC records for O365 safely. Configure SPF and DKIM, publish the right TXT record, interpret reports, and progress to reject.
Jul 28, 202620 min read
DMARC Record Microsoft 365: Complete Setup, Testing, and Enforcement Guide
Set up a DMARC record for Microsoft 365 with correct SPF, DKIM, reporting, testing, and a safe path from monitoring to enforcement.
Jul 28, 202619 min read
DMARC Record Syntax: Every Tag, Example, and Setup Step
Learn correct DMARC record syntax, what every tag does, how to publish a TXT record, and how to move safely from monitoring to reject.
Jul 27, 202620 min read
DMARC Record Generator: Build, Publish, and Validate Your Policy
Use this DMARC record generator guide to create the right DNS TXT record, collect reports, enforce safely, and validate SPF and DKIM alignment.
Jul 27, 202618 min read
DMARC Record Builder: Create, Publish, and Verify Your DMARC Policy
Use this DMARC record builder to create a valid DNS TXT record, choose a safe policy, collect reports, and verify SPF and DKIM alignment.
Jul 27, 202620 min read
DMARC Record Errors: How to Find, Fix, and Prevent Them
Fix DMARC record errors with a practical checklist for DNS syntax, SPF and DKIM alignment, reporting, policies, testing, and validation.
Jul 27, 202621 min read
Email Authentication Setup: SPF, DKIM, and DMARC Step by Step
Complete email authentication setup guide: add SPF, DKIM, and DMARC DNS records, test alignment, fix errors, and protect delivery.
Jul 27, 202619 min read
Email Authentication Records: Set Up SPF, DKIM, and DMARC Correctly
Learn how to create, validate, and troubleshoot email authentication records for SPF, DKIM, and DMARC with practical DNS examples.
Jul 26, 202623 min read
DMARC Record Setup: A Practical DNS Guide From Monitoring to Reject
Set up a DMARC record with correct DNS syntax, SPF and DKIM alignment, reporting, staged enforcement, testing, and fixes for failures.
Jul 26, 202620 min read
SPF, DKIM, and DMARC Setup: A Practical DNS Guide That Works
Learn SPF DKIM DMARC setup step by step: create correct DNS records, validate alignment, monitor reports, and safely enforce anti-spoofing.
Jul 25, 202619 min read