What’s the difference between MX and A record routing?
MX routing: The standard, correct method. Senders look up MX records to find mail servers.
A record fallback: If no MX records exist, RFC 5321 allows trying the domain's A record as the mail server.
Differences:
Flexibility: MX records can point to different servers than your web server. A record fallback uses the same IP.
Priority: MX supports multiple servers with priorities. A record fallback has no redundancy.
Reliability: Many senders do not implement A record fallback. MX is universally supported.
Never rely on A record fallback. Always configure proper MX records.
MX is the official mail delivery address. A record fallback is like sending packages to the general business address and hoping.
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