Runs in your browser
MX lookup
Mail servers, sorted by priority.
The lookup goes from your browser straight to a public service. We never see the domain.
What this checks
MX records list the mail servers that accept email for a domain, each with a priority number. This tool reads them and sorts them lowest first.
What to look for
The lowest priority number is tried first; higher numbers are backups. A domain with no MX records cannot receive email at all, even if its website works fine — the two are served by separate DNS records.
One record, one job
A single MX pointing straight at the domain's own web server usually means there is no real mail setup, or a fallback with no redundancy if that one server goes down.