Blog
Email Deliverability Guides & Best Practices
Guides, best practices, and intelligence from the InboxEagle team to help you land in the inbox every time.
E-commerce9 min
Email List Hygiene: The Deliverability Practice Most eCommerce Brands Skip
Email list hygiene is one of the highest-leverage deliverability practices for eCommerce brands — yet most skip it until a crisis forces their hand. Here's exactly what it is, why it matters, and how to diagnose and fix list decay in Klaviyo.
Authentication6 min
Why Your "Mailed-By" Domain Matters for Brand Trust
82.8% of marketing emails display a third-party mailed-by domain in Gmail. Here's what that signals to your subscribers and why it's quietly costing you deliverability equity.
E-commerce13 min
Monitor Email Delivery in Real Time: Deliverability Guide
How to monitor email delivery in real time: the email deliverability metrics to monitor, the email deliverability monitoring tools that surface them, and how to act before a problem becomes a crisis.
Analytics9 min
List-Unsubscribe Header: Does It Actually Reduce Spam Rates?
Does the List-Unsubscribe header actually lower spam rates? InboxEagle's study of 19,797 brands reveals a 4.86x extreme spam risk for senders without it.
Klaviyo9 min
Setting Up a Custom Sending Domain in Klaviyo: Step by Step
A complete guide to setting up a Klaviyo custom sending domain — with DNS records, authentication verification, and why it matters for deliverability.
Authentication6 min
MTA-STS and TLS-RPT: The Email Security Standards Most Brands Miss
SPF, DKIM, and DMARC get all the attention — but MTA-STS and TLS-RPT are the two DNS records that complete your domain's email security posture. Here's what they do, why they matter, and how to set them up.
Authentication7 min
The Technical Anatomy of a Perfect Ecommerce Email Header
InboxEagle analyzed 256,606 emails across 16,381 brands. Only 16.7% had a perfect header. Here's what separates them from the rest — and how to fix yours.
Analytics8 min
The Correlation Between High Sending Frequency & Spam Complaints
Does sending more emails mean more spam complaints? InboxEagle analyzed 31,586 sending programs — the data tells a more nuanced story than you think.
Gmail8 min
Gmail Spam Rate Thresholds: What 0.10% and 0.30% Actually Mean for You
Google sets two spam rate numbers that most senders misread. Here's exactly what 0.10% and 0.30% mean, how they're measured, and what to do before you breach either one.
Authentication11 min
12 Email Marketing Mistakes Killing Your Deliverability in 2026
Sending but not landing? These 12 email marketing mistakes — from skipped authentication to bought lists — are the most common reasons emails go to spam. Learn what to fix.
E-commerce6 min
What Is a Sending Domain and Why Does It Need Its Own Reputation?
Your sending domain is the identity your email program lives or dies by — and it's separate from your website. Here's what it is, why it needs its own reputation, and what most Klaviyo senders get wrong about it.
E-commerce7 min
Email Domain Reputation Score: How It's Scored and Protected
Email domain reputation is the primary signal ISPs use to route your campaigns. Here's exactly how it's scored, what damages it fastest, and how to protect it before the next send.