X.400 mail mapping information
Quick facts
Purpose
X.400 mail mapping information
PX is one of the DNS resource record (RR) types defined by RFC 2163.
Related record types
Frequently asked questions
Used for DNS resolution and zone configuration.
In the DNS management panel of your registrar or DNS provider (for example Cloudflare or Route53).
Sources & standards
Updated 2026-08-18
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