What this tool does
Returns a domain's MX (Mail Exchange) records in priority order — the first thing to check when inbound mail isn't being routed to the expected mail server, or when setting up a new mail provider.
Reading priority values
Lower priority numbers are tried first. A domain with multiple MX records is typically using the lowest-priority one as primary and higher-priority ones as backups if the primary is unreachable — mail servers attempt delivery in that order automatically.
When you'd use this
Verifying a migration to a new email provider has fully propagated before decommissioning the old mail server, or diagnosing why inbound mail is bouncing or being misdirected.