An MX record tells the internet where to send email for your domain. Mail servers query your DNS to find the hostname and priority of your mail server, then deliver messages there instead of to your domain itself.
You need at least one MX record pointing to a mail server you control or trust. Multiple MX records with different priorities let you run failover: if the primary mail server is down, the sender tries the next one in line.
Example: `mail.example.com 10` means "try this mail server first." `mail2.example.com 20` means "if that fails, try this one." Lower priority numbers are tried first.
Why it matters: without an MX record, email sent to you@yourdomain.com bounces. Your domain can host a website, but email goes nowhere. If you run a mail server yourself or use a third-party mail provider, you must create an MX record pointing to their infrastructure.
For anonymous or offshore operations: if your mail server is bulletproof hosting, your MX record becomes part of your infrastructure fingerprint. Some registrars log MX changes; we don't. Using a mail provider in a jurisdiction hostile to DMCA or government pressure adds practical resilience.