MX records say which servers accept a domain's mail. No MX, no inbox: emails to that domain will bounce.
Privacy: this tool runs entirely in your browser. When you click Check, one DNS query for the domain you typed goes to Cloudflare's public DNS resolver (Google's as fallback). Nothing is stored, logged or sent to GrowthPal.
Three practical reasons. Before a campaign: a domain with no MX will bounce, and bounces poison your sender reputation. During diagnosis: the MX host tells you who filters the target's mail, and a Proofpoint or Mimecast gateway explains a lot of silence. And on your own sending domains: MX records are part of looking like a real mailbox rather than a blast cannon.
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