Infrastructure

MX Record

A DNS record that specifies the mail server responsible for accepting email for a domain.

MX (Mail Exchanger) records are DNS entries that direct email to the correct mail server. When someone sends an email to user@example.com, the sending server looks up example.com's MX records to find which server to deliver to.

Example MX records: `` example.com MX 10 aspmx.l.google.com example.com MX 20 alt1.aspmx.l.google.com ``

The priority number (10, 20) determines which server to try first — lower numbers have higher priority.

What MX records reveal during verification:

  • No MX records: The domain can't receive email — addresses are invalid
  • Google MX records: Domain uses Google Workspace
  • Microsoft MX records: Domain uses Microsoft 365
  • Provider detection: Helps determine verification strategy

SendSure checks MX records at stage 2 of the 27-stage verification process. A missing or invalid MX record immediately classifies the email as invalid without needing further SMTP checks.

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