Blog
Email Deliverability Guides & Best Practices
Guides, best practices, and intelligence from the InboxEagle team to help you land in the inbox every time.
Analytics8 min
Do Spam Trigger Words Really Cause Spam? 774K Emails Tested
Do spam trigger words like 'free' and 'sale' actually send emails to spam? We analyzed 774,828 emails from Q1 2026. The findings may surprise you.
Analytics9 min
How to Check Your Email Sender Reputation Score
Your sender reputation score determines inbox or spam — before you hit send. Here's how to check it for free across Gmail, Outlook, and enterprise infrastructure, and what to do when the numbers are bad.
E-commerce7 min
Email Sunset Policy: The Data Behind a 3× Spam Rate Gap
InboxEagle analyzed 16,356 ecommerce senders. Low-volume programs average a 56% spam rate. High-volume programs average 18%. The difference is a sunset policy.
Klaviyo9 min
Klaviyo Suppression Lists: How to Use Them to Protect Deliverability
Klaviyo suppression list: five suppression types, global vs. list-level scope, what can be reversed, the billing distinction most brands miss, and how to use it to actively protect inbox placement.
Authentication5 min
Email Authentication for Klaviyo Senders: The Complete Guide
Email authentication is the foundation of inbox placement for every Klaviyo sender. Here's what SPF, DKIM, and DMARC actually do, why Klaviyo's default setup breaks DMARC alignment, and where to go deeper on each.
E-commerce8 min
Email Deliverability for Agencies: How to Manage Multiple Client Domains
Managing email deliverability across multiple client domains is one of the hardest operational challenges in eCommerce agency work. Here's the framework — domain isolation, monitoring at scale, and the mistakes that cause one client to hurt another.
E-commerce8 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-commerce10 min
How to Monitor Your Email Deliverability in Real Time
A practical guide to email deliverability monitoring in real time — the signals that matter, the tools that surface them, and how to act before a problem becomes a crisis.
Analytics8 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.
Klaviyo8 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.