Look up and rank a domain’s MX records by priority. Useful for verifying email-provider migrations, checking inbound spam-filter setups, and confirming new domain bring-up.
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A Mail Exchanger (MX) record tells the world which servers accept email for a domain, and in what order. Senders try the lowest-preference (highest-priority) server first; ties are broken by random selection so traffic is distributed.
It works, but it’s fragile. If that server is down nobody can deliver mail. Modern providers publish 2–4 MXes with different preferences (10, 20, 30) so RFC-compliant senders fall back automatically.
Senders may fall back to A/AAAA records (the “implicit MX”) or simply give up. For production mail you should always publish at least one MX, even if it points to a third-party provider like Google Workspace or Microsoft 365.
Generally no. Modern senders queue mail for days. A poorly-configured backup MX is more often a spam-spool than a useful failover. Stick with your primary provider’s redundant MXes.