Password-Protect a Directory with .htaccess: Basic Auth, APR1-MD5, and bcrypt
Basic Auth, .htaccess/.htpasswd, file permissions, and APR1-MD5 vs bcrypt hashing: everything you need to protect a sensitive directory on Apache or nginx.
CaptainDNS Blog
DNS, email authentication, AI integrations and product updates.
Technical guides, comparisons and insights on public DNS resolvers (Cloudflare, Google, Quad9), email authentication (SPF, DKIM, DMARC, BIMI, ARC) and deliverability. Learn how to configure Amazon SES, Brevo, SendGrid or Mailjet, and explore our AI integrations with ChatGPT and the MCP protocol. Whether you're a sysadmin, developer or marketing manager, find best practices here to secure your domains and optimize your email delivery.
Articles
August 2026
July 2026
SSL certificate renewal automation: inventory, the endpoints ACME can't reach, and when to pay
Fleet inventory, enterprise ACME, endpoints no script can reload, Let's Encrypt rate limits and DCV reuse: the field playbook for SSL certificate renewal automation across 50 to 1,000 certificates.
Certificate Lifecycle Management (CLM): the complete guide to surviving short-lived certificates
Inventory, issuance, deployment, renewal, revocation, monitoring: the 6 phases of the certificate lifecycle, ACME/ARI automation, and an action plan to keep up with 47-day renewals.
June 2026
Hornetsecurity Secure Email Gateway (ex-Vade): architecture, DNS configuration and alternatives
Hornetsecurity 365 Total Protection is the cloud SEG for SMBs and MSPs (ex-Vade, now Proofpoint). Complete guide: architecture, mx01.hornetsecurity.com MX, spf.hornetsecurity.com SPF include, DKIM by CNAME, gateway vs API and a comparison with Proofpoint/Barracuda/Mimecast.
Barracuda Email Gateway Defense: architecture, DNS configuration and alternatives
Barracuda Email Gateway Defense is the cloud SEG for SMBs and MSPs (200,000+ customers). Complete guide: architecture, *.ess.barracudanetworks.com MX, SPF/DKIM/DMARC, DNS detection, the distinction with the ESG appliance (CVE-2023-2868) and a comparison with Mimecast/Proofpoint/Defender.
CAA DNS records: the complete guide to controlling who issues your certificates
Everything about the CAA DNS record: syntax, issue/issuewild/iodef tags, critical flag, inheritance, RFC 8659 and 8657, multi-provider setup, and auditing.
ARC moves to "Historic" status at the IETF: should you still care in 2026?
The IETF is reclassifying ARC (RFC 8617) as "Historic." But deprecated on paper does not mean dead in practice: Apple, Google and Microsoft still require it. Here is what really changes and what you should do.
May 2026
Email deliverability score: what it's made of and how to improve it
The email deliverability score is not a black box. It rests on five measurable pillars: authentication, reputation, transport security, BIMI and engagement. This guide breaks them down and gives the thresholds to aim for.