SPF, DKIM, and DMARC Explained: How They Work Together
Want SPF, DKIM, and DMARC explained without the vendor sales pitch? Each protocol solves part of email spoofing. Here is what they do, how they work together, and what to set up first.
Security
Firewalls, port numbers, traffic filtering, and the fundamentals of securing network infrastructure.
What Is a DNS Blacklist? (And How to Get Off One)
Need to remove your IP from an email blacklist? Spamhaus, Barracuda, and SpamCop each have different processes. Here is what a DNS blacklist actually is, why SORBS no longer matters, and the steps that work.
How to Set Up SPF and DMARC Without Breaking Email
Need to set up SPF and DMARC without breaking email delivery? The safe order matters more than the records themselves. Here is the staged playbook — inventory senders first, publish in order, monitor before enforcing.
How SSL Certificates Work (And What to Do When They Expire)
Want to know how SSL certificates work without the marketing fluff? They prove a server’s identity using a chain of trust. Here is what changed in March 2026, and what to do when one expires.
What Is a Firewall? Ports, Rules, and Traffic Filtering
TL;DR — The Short Version A firewall monitors and controls network traffic based on a predefined set of rules. It sits between trusted and untrusted networks. Decisions come from packet headers. Source and destination IP, port numbers, and protocol determine whether traffic is allowed, denied, or dropped. Types range from simple to deep. Stateless packet … Read more