SMTP Error Code: 421 2.1.4

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Lookup for "421 2.1.4"

This status code indicates a successful delivery or other operation. Any details are simply notes.

Basic Status Code Details (421)

Service not available, closing transmission channel [This may be a reply to any command if the service knows it must shut down]

Enhanced Status Code Details (2.1.4)

Destination mailbox address ambiguous

The mailbox address as specified matches one or more recipients on the destination system. This may result if a heuristic address mapping algorithm is used to map the specified address to a local mailbox name.