The Axvoid Tools Blog
Practical, source-backed guides on email deliverability, list hygiene, campaign testing and tracking — each one connected to a free tool you can use right now.
🛡️ Email Authentication & Deliverability
SPF, DKIM, DMARC, headers and unsubscribe standards explained with step-by-step fixes.
Email Authentication & DeliverabilityHow to Read Email Headers: A Step-by-Step Guide to Tracing Any Message
Learn how to read email headers: view them in Gmail and Outlook, follow the Received chain and read SPF, DKIM and DMARC results step by step.
10 min read
Email Authentication & DeliverabilityList-Unsubscribe Header: How to Set Up One-Click Unsubscribe the Right Way
Set up the List-Unsubscribe and List-Unsubscribe-Post headers: RFC 8058 syntax, endpoint rules, DKIM signing, testing and Gmail and Yahoo requirements.
8 min read
Email Authentication & DeliverabilityGmail and Yahoo Bulk Sender Requirements: The Complete Compliance Checklist
A practical checklist for Gmail and Yahoo bulk sender rules: SPF, DKIM, DMARC, one-click unsubscribe and the 0.3% spam rate limit, with how to verify each.
7 min read
Email Authentication & DeliverabilitySPF Record for Google Workspace, SendGrid and Other Providers: How to Combine Them Safely
How to write one SPF record for several email providers: syntax, include examples, the 10-lookup limit and a safe rollout from ~all to -all.
7 min read🧹 List Hygiene & Validation
Validate, extract and clean email lists without hurting your sender reputation.
✉️ Campaign Content & Optimization
Subject lines, spam triggers and content decisions backed by how filters and clients really behave.
📊 Measurement & Testing
Metrics, formulas, A/B tests and tracking links you can trust.
Measurement & TestingUTM Parameters for Email Campaigns: A Naming Convention That Keeps Your Data Clean
UTM parameters for email campaigns: what each does in GA4, a consistent naming convention with examples and the mistakes that corrupt reports.
5 min read
Measurement & TestingEmail Marketing Metrics Formulas: How to Calculate Open Rate, CTR, CTOR and Bounce Rate
Exact formulas for open rate, CTR, CTOR, bounce, unsubscribe and complaint rate, with a worked example and the pitfalls that distort them.
7 min read
Measurement & TestingEmail A/B Test Sample Size: How Many Subscribers You Need for a Reliable Result
How to calculate email A/B test sample size and read significance correctly: baseline, minimum effect, power, duration and common mistakes.
6 min read🔗 Everyday Utilities
Small, practical how-tos for links, text and day-to-day email tasks.
