Domain name with or without accents: what changes for your email
Removing an accent changes the domain name. Find the right DNS zone behind its displayed form and understand the consequences for SPF, DKIM and DMARC.
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
September 2026
August 2026
Domain without email: the Null MX configuration
An explicit DNS zone for a website without email or a defensive domain: Null MX, strict SPF, DMARC reject, no DKIM selector, and an appropriate CAA policy.
Gmail verifies the sender, not the desire to receive those emails
Gmail's program for U.S. political committees does not promise the inbox. It formalizes a known rule: identity opens the door, reputation decides what follows.
New gTLD 2026: what we know after the application window closed
More than 1,600 primary applications were submitted. Here are the confirmed figures, the unknowns, and the timeline to watch after August 12, 2026.
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.
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.