SMTP Error Code: 421 2.4.5

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Lookup for "421 2.4.5"

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 (2.4.5)

Mail system congestion

The mail system was unable to deliver the message because the mail system was congested. This is useful only as a persistent transient error.