015.008

Infrastructure & DNS Bounces

The "I can't find your harbor" bounce. This section covers technical bounces, like "DNS lookup failed" (your domain is broken) or "Connection timed out" (your server is offline). These are the 'engine failure' alerts for your ship.

12 questions in this topic

What is a DNS-related bounce? What causes “host not found”? What causes “invalid MX record”? What happens when DNS fails mid-transaction? What’s the difference between “connection timed out” and “refused”? How can DNS propagation cause delivery errors? How do CNAME or tracking domain errors trigger bounces? What is an “unresolvable hostname”? What are SSL/TLS handshake failures? What is “certificate mismatch”? How do expired certificates cause bounces? How do relay errors differ from DNS issues?