Email Deliverability Blog
Tips, news, and insights to help you reach the inbox.
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CAN-SPAM Act Compliance: Every Requirement Email Senders Must Follow
The CAN-SPAM Act sets federal rules for commercial email in the United States. Learn every requirement, how to stay compliant, and the penalties for violations.
Read more →DMARC Alignment Explained: Strict vs Relaxed and How to Fix Failures
DMARC alignment requires that the domains used by SPF or DKIM match your visible From address. Learn the difference between strict and relaxed alignment, common failure scenarios, and how to fix them.
Read more →Email Suppression Lists: How to Build and Manage Them for Deliverability
An email suppression list prevents you from sending to addresses that would damage your sender reputation. Learn what belongs on one, how to maintain it across platforms, and why it is critical for deliverability.
Read more →Email Throttling Explained: Why Mailbox Providers Slow Your Sends and How to Prevent It
Email throttling happens when receiving servers limit how many of your emails they accept per hour or day. Learn why it happens, how to spot it, and how to prevent it from harming your deliverability.
Read more →Sender Reputation Recovery: How to Rebuild Deliverability After a Crisis
When your sender reputation takes a hit, recovery requires a disciplined, phased approach. Learn the step-by-step process to diagnose damage, rebuild trust with mailbox providers, and restore inbox placement.
Read more →Email Spam Complaint Rate: How to Monitor and Stay Below the 0.3% Threshold
Gmail and Yahoo enforce a hard 0.3% spam complaint rate threshold for bulk senders. Learn how complaint rates are calculated, how to monitor yours, and the proven strategies to keep it safely below the limit.
Read more →Email Spam Traps Explained: Types, Risks, and How to Avoid Them
Spam traps silently destroy sender reputation and trigger blacklisting. Learn what spam traps are, the three types you need to watch for, and the proven strategies to keep them off your list.
Read more →Outlook Sender Requirements: What High-Volume Senders Must Do to Avoid Filtering and Rejection
Microsoft now requires SPF, DKIM, and DMARC for senders sending 5,000+ emails per day to Outlook.com domains. Learn exactly what to configure, what happens if you do not comply, and how to verify your setup.
Read more →Microsoft SNDS: The Complete Setup and Monitoring Guide
Learn how to set up and use Microsoft Smart Network Data Services (SNDS) to monitor your IP reputation, track spam complaints, and improve deliverability to Outlook, Hotmail, and Live.com recipients.
Read more →Email List Hygiene: How to Clean Your List and Protect Deliverability
Learn how to maintain a clean email list with proven hygiene practices that reduce bounces, avoid spam traps, and protect your sender reputation.
Read more →Email Engagement Signals: How Mailbox Providers Use Them to Decide Inbox vs Spam
Learn which engagement signals mailbox providers track, how opens, clicks, replies, and complaints influence inbox placement, and how to optimize your sending for maximum engagement.
Read more →Microsoft SNDS: How to Monitor Your Outlook and Hotmail Deliverability
Learn how to set up Microsoft Smart Network Data Services (SNDS) to monitor your IP reputation, spam filter results, complaint rates, and trap hits for Outlook and Hotmail delivery.
Read more →DKIM Key Rotation: Why It Matters and How to Rotate Keys Without Downtime
Learn why rotating DKIM keys is essential for email security, how often to do it, the right key lengths to use, and a step-by-step process for zero-downtime rotation.
Read more →Email Feedback Loops Explained: How Spam Complaints Reach Senders
Learn how email feedback loops (FBLs) work, how Gmail, Yahoo, and Microsoft handle complaint reporting differently, and how to register and use FBLs to protect your sender reputation.
Read more →Google Postmaster Tools: The Complete Setup and Monitoring Guide
Learn how to set up Google Postmaster Tools, interpret every dashboard metric, and use the data to protect your sender reputation and improve Gmail inbox placement.
Read more →BIMI Explained: How to Display Your Brand Logo in the Email Inbox
Learn what BIMI (Brand Indicators for Message Identification) is, how it works, and how to set it up step by step to display your verified brand logo in Gmail, Yahoo, and Apple Mail inboxes.
Read more →How Email Spam Filters Work: The Signals Mailbox Providers Use to Decide Inbox vs Spam
Understand exactly how Gmail, Outlook, and Yahoo decide whether your email reaches the inbox or gets filtered to spam. Covers authentication checks, reputation scoring, engagement signals, content analysis, and behavioral filtering.
Read more →SPF Too Many DNS Lookups: How to Fix the 10 Lookup Limit and PermError
Getting an SPF PermError due to too many DNS lookups? Learn why the 10 lookup limit exists, how to count your lookups, and five proven methods to fix the problem without breaking email delivery.
Read more →Why Are My Emails Going to Spam? Every Cause and How to Fix It
Emails landing in spam instead of the inbox? This comprehensive guide covers every reason emails get flagged, from authentication failures and poor sender reputation to content triggers and list quality, with step-by-step fixes for each.
Read more →DMARC Policy: p=none vs p=quarantine vs p=reject and How to Reach Full Enforcement
Understand the three DMARC policy levels, what each one does to unauthenticated email, and how to safely progress from monitoring to full reject enforcement.
Read more →DMARC Reports Explained: How to Read and Analyze Aggregate and Forensic Reports
Learn how to read DMARC aggregate XML reports, understand forensic failure reports, and use DMARC reporting data to fix authentication issues and reach policy enforcement.
Read more →IP and Domain Warmup: The Complete Guide to Building Sender Reputation from Scratch
Learn how to warm up a new IP address or domain for email sending. Includes a day-by-day ramp-up schedule, engagement strategies, and common warmup mistakes to avoid.
Read more →Gmail Promotions Tab: How It Works, Why Emails Land There, and What Senders Should Do
Understand how Gmail decides which emails go to the Promotions tab vs Primary inbox, what the 2025 relevance-based sorting changes mean, and how to optimize your email strategy.
Read more →Inbox Placement Rate vs Email Delivery Rate: Understanding the Metrics That Actually Matter
Email delivery rate and inbox placement rate measure very different things. Learn the critical difference and why inbox placement is the metric you should be tracking.
Read more →Email Sunset Policy: How to Manage Inactive Subscribers and Protect Deliverability
Learn how to build an effective email sunset policy that removes inactive subscribers, improves engagement metrics, and safeguards your sender reputation.
Read more →Graylisting Explained: Why Your Emails Get Temporarily Rejected and How to Handle It
Learn what graylisting is, why mail servers use it to fight spam, how it affects your email delivery, and what you can do to minimize delays caused by temporary rejections.
Read more →Email Subdomain Strategy: How to Isolate and Protect Your Sender Reputation
Learn why separating your email streams onto dedicated subdomains protects your sender reputation, improves deliverability, and gives you granular control over each sending channel.
Read more →Bulk Email Best Practices in 2026: The Complete Deliverability Guide
Everything you need to know about sending bulk email in 2026, from authentication requirements to engagement optimization, list management, and compliance with the latest sender standards.
Read more →List-Unsubscribe Header and One-Click Unsubscribe: Complete Implementation Guide
Learn how to implement the List-Unsubscribe header and RFC 8058 one-click unsubscribe to meet Google and Yahoo sender requirements and reduce spam complaints.
Read more →Email Deliverability Audit: The Complete Checklist for Diagnosing Inbox Issues
A step-by-step email deliverability audit checklist covering authentication, reputation, infrastructure, content, and list quality to identify and fix inbox placement problems.
Read more →Double Opt-In Email: Why It Matters and How to Set It Up
Double opt-in email verification confirms every subscriber genuinely wants your emails, dramatically improving deliverability and protecting your sender reputation.
Read more →Email Blacklist Check and Removal: How to Get Delisted and Stay Clean
Learn how to check if your IP or domain is blacklisted, fix the root cause, request removal from major blacklists, and prevent future listings.
Read more →MTA-STS and TLS-RPT Explained: Securing Email in Transit
Learn how MTA-STS enforces TLS encryption on inbound email delivery and how TLS-RPT provides reporting on connection failures to protect against downgrade attacks.
Read more →SMTP Error Codes and Bounce Messages Explained: Complete Reference Guide
Learn what every SMTP error code means, from 421 temporary deferrals to 550 permanent rejections, and how to diagnose and fix email delivery failures.
Read more →ARC (Authenticated Received Chain) Explained: How It Fixes Email Forwarding Authentication Failures
Learn how ARC preserves email authentication results when messages are forwarded or relayed, preventing legitimate emails from failing DMARC checks and landing in spam.
Read more →Email Throttling and Rate Limiting: What They Mean and How to Avoid Delivery Delays
Understand how email throttling and rate limiting work, why ISPs defer your messages, how to recognize throttling in your bounce logs, and strategies to prevent it.
Read more →Hard Bounce vs Soft Bounce in Email: What They Mean and How to Fix Them
Learn the difference between hard bounces and soft bounces, what causes each type, how they impact your sender reputation, and actionable steps to reduce your bounce rate.
Read more →Email Headers Explained: How to Read and Analyze Them for Deliverability
Email headers contain critical diagnostic data about authentication, routing, and spam filtering. Learn how to read, interpret, and use headers to troubleshoot deliverability issues.
Read more →Email Domain Reputation: How to Check, Monitor, and Improve It
Your email domain reputation determines whether messages reach the inbox or land in spam. Learn how it works, which tools to use for monitoring, and actionable strategies to improve it.
Read more →Email Spam Traps Explained: Types, Risks, and How to Avoid Them
Learn what email spam traps are, the three main types (pristine, recycled, and typo), how they damage your sender reputation, and proven strategies to keep your lists clean.
Read more →Transactional Email vs Marketing Email: Deliverability Best Practices
Learn the key differences between transactional and marketing email, why separating them protects your sender reputation, and how to configure your infrastructure for optimal deliverability.
Read more →Email Spam Complaint Rate: How to Monitor, Calculate, and Reduce It
Learn what a spam complaint rate is, how it is calculated, what thresholds major providers enforce, and proven strategies to keep your complaint rate below 0.1%.
Read more →PTR Records and Reverse DNS: Why They Matter for Email Deliverability
Learn how PTR records and reverse DNS (rDNS) work, why they are required for email delivery, and how to set up Forward-Confirmed rDNS to pass mailbox provider checks.
Read more →DKIM Record Explained: How DomainKeys Identified Mail Works
Learn how DKIM uses public-key cryptography to authenticate your emails, prevent spoofing, and improve deliverability. Complete guide to DKIM records, selectors, signatures, and setup.
Read more →Dedicated IP vs Shared IP for Email: Which Is Right for You?
Should you use a dedicated IP or shared IP for email sending? Learn the differences, pros and cons, and how each option impacts your sender reputation and deliverability.
Read more →Email List Hygiene: The Complete Guide to Cleaning Your Email List
Learn how to clean your email list, remove spam traps, reduce bounces, and protect your sender reputation with this step-by-step list hygiene guide.
Read more →Email Feedback Loops (FBL): Complete Setup and Monitoring Guide
Learn how email feedback loops work, how to register with every major ISP, and how to use complaint data to protect your sender reputation and improve deliverability.
Read more →Google Postmaster Tools: Complete Setup and Monitoring Guide
Learn how to set up Google Postmaster Tools, interpret the new V2 compliance dashboards, and use spam rate data to protect your sender reputation and improve Gmail inbox placement.
Read more →BIMI Record Setup Guide: Display Your Brand Logo in Email Inboxes
Learn how to set up BIMI (Brand Indicators for Message Identification) to display your verified brand logo in recipient inboxes. Step-by-step DNS setup, logo requirements, VMC vs CMC certificates, and troubleshooting tips.
Read more →Microsoft Outlook 2025 Sender Requirements: Complete Compliance Guide
Microsoft now enforces SPF, DKIM, and DMARC for bulk senders targeting Outlook.com, Hotmail, and Live.com. Learn exactly what changed and how to comply.
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