Learning Center

Deep guides for people who actually fix broken domains.

Fourteen practical guides on email authentication, DNS, SSL, and uptime. No fluff, no SEO filler, written by people who debug this stuff for a living.

SPF12 min read

SPF Records. The Complete Guide

What SPF is, why mailbox providers care, and how to author a record that doesn't break in six months.

Read guide
DKIM10 min read

DKIM. How to Sign Your Email Properly

The cryptographic signature that proves your email came from you. Selectors, key rotation, and the gotchas no one tells you about.

Read guide
DMARC14 min read

DMARC. From Monitor-Only to Reject

A practical, no-fear path from p=none to p=reject. Aggregate reports, alignment, and the moves that actually move the needle.

Read guide
MX7 min read

MX Records. Email Routing for Humans

How mail finds your servers, what priorities really do, and the most common ways MX setups silently break.

Read guide
Blacklists9 min read

IP Blacklists. Get Off, Stay Off

What gets you listed on Spamhaus, how to request delisting, and how to keep a clean sending reputation long-term.

Read guide
SSL8 min read

SSL/TLS Certificates. Don't Get Caught Expired

How certs work in 2026, why auto-renew quietly fails, and how to sleep through Let's Encrypt rotations.

Read guide
Domain Expiry6 min read

Domain Expiry. How Not to Lose Your Business

The horror stories are real. Auto-renew can fail. Here's how to make sure you're never the next cautionary tale.

Read guide
Uptime7 min read

HTTP Uptime. More Than a Green Dot

Real uptime monitoring means catching slow responses, partial outages, and SSL handshake failures, not just "the page loaded".

Read guide
DNSSEC9 min read

DNSSEC. Signing Your DNS Without Breaking It

Cryptographic proof that your DNS answers are real. Why it matters, how to enable it safely, and the one mistake that takes your whole domain offline.

Read guide
MTA-STS9 min read

MTA-STS. Enforce TLS for Inbound Mail

SMTP encryption is opportunistic by default, attackers can strip it. MTA-STS lets you demand TLS for mail sent to your domain.

Read guide
TLS-RPT7 min read

TLS-RPT. Know When Mail Encryption Fails

One TXT record gets you daily reports from Google and Microsoft whenever TLS to your mail servers breaks. Almost nobody publishes it.

Read guide
BIMI9 min read

BIMI. Get Your Logo in the Inbox

The DNS record that puts your brand logo next to your emails in Gmail and Yahoo, and the DMARC enforcement bar you must clear first.

Read guide
CAA7 min read

CAA Records. Control Who Issues Your Certificates

A two-line DNS record that stops any certificate authority you haven't approved from issuing certs for your domain.

Read guide
rDNS7 min read

Reverse DNS. The PTR Record Mail Servers Demand

No PTR record, no inbox. Why reverse DNS is a hard requirement for sending mail, and how to set it with your hosting provider.

Read guide
Bulk Sender Rules9 min read

Gmail and Yahoo Bulk Sender Requirements in 2026. The Complete Checklist

Send 5,000+ messages a day to Gmail or Yahoo? You need SPF, DKIM, DMARC alignment, one-click unsubscribe, and a spam rate under 0.3%. Every requirement, with the exact records.

Read guide
DMARC Policies9 min read

DMARC p=none vs quarantine vs reject. Which Policy Should You Run?

The p= tag is a staircase, not a preference. What none, quarantine, and reject each do — and the safe migration path that gets you to reject without bouncing your own mail.

Read guide