Mar 162015
 

SMTP Error Codes

Here is a list of the standard SMTP error codes you will find in most email bounces.

200 Codes

  • 211 – System status / system help reply
  • 214 – Help message
  • 220 – Domain service ready
  • 221 – Domain service closing transmission channel
  • 250 – Requested mail action completed and OK
  • 251 – Not Local User, forward email to forward path
  • 252 – Cannot Verify user, will attempt delivery later
  • 253 – Pending messages for node started

300 Codes

  • 354 – Start mail input; end with .
  • 355 – Octet-offset is the transaction offset

400 Codes

  • 421 – Domain service not available, closing transmission channel
  • 432 – Domain service not available, closing transmission channel
  • 450 – Requested mail action not taken: mailbox unavailable. request refused
  • 451 – Requested action aborted: local error in processing Request is unable to be processed, try again
  • 452 – Requested action not taken: insufficient system storage
  • 453 – No mail
  • 454 – TLS not available due to temporary reason. Encryption required for requested authentication mechanism
  • 458 – Unable to queue messages for node
  • 459 – Node not allowed: reason

500 Codes

  • 500 – Syntax error, command unrecognized
  • 501 – Syntax error in parameters or arguments
  • 502 – Command not implemented
  • 503 – Bad sequence of commands
  • 504 – Command parameter not implemented
  • 510 – Check the recipient address
  • 512 – Domain can not be found. Unknown host.
  • 515 – Destination mailbox address invalid
  • 517 – Problem with senders mail attribute, check properties
  • 521 – Domain does not accept mail
  • 522 – Recipient has exceeded mailbox limit
  • 523 – Server limit exceeded. Message too large
  • 530 – Access Denied. Authentication required
  • 531 – Mail system Full
  • 533 – Remote server has insufficient disk space to hold email
  • 534 – Authentication mechanism is too weak. Message too big
  • 535 – Multiple servers using same IP. Required Authentication
  • 538 – Encryption required for requested authentication mechanism
  • 540 – Email address has no DNS Server
  • 541 – No response from host
  • 542 – Bad Connection
  • 543 – Routing server failure. No available route
  • 546 – Email looping
  • 547 – Delivery time-out
  • 550 – Requested action not taken: mailbox unavailable
  • 551 – User not local; please try forward path
  • 552 – Requested mail action aborted: exceeded storage allocation
  • 553 – Requested action not taken: mailbox name not allowed
  • 554 – Transaction failed

Extended SMTP (ESMTP) standards

Extended SMTP error codes are used in 3 digit combinations. For example, 4.2.1 is a Temporary Error where the receiving email is not accepting messages for now.

The first number is the email message status.

  • 2 Successfully sent the email;
  • 4 Temporary problem when sending the email. The email server typically will try to send it again till it reaches retry timeout.
  • 5 Permanent or Fatal error. This can be caused by a non existent email address, DNS problem, or your email was blocked by the receiving server.

The second 2 numbers pinpoint the exact information bout the error.

Below is a list of the Extended SMTP error codes.

Note! X can be a 4 or a 5 depending on if it is a Temporary or Permanent error.

x.1.x Codes

  • X.1.0 – Other address status
  • X.1.1 – Bad destination mailbox address
  • X.1.2 – Bad destination system address
  • X.1.3 – Bad destination mailbox address syntax
  • X.1.4 – Destination mailbox address ambiguous
  • X.1.5 – Destination mailbox address valid
  • X.1.6 – Mailbox has moved
  • X.1.7 – Bad sender’s mailbox address syntax
  • X.1.8 – Bad sender’s system address

x.2.x Codes

  • X.2.0 – Other or undefined mailbox status
  • X.2.1 – Mailbox disabled, not accepting messages
  • X.2.2 – Mailbox full
  • X.2.3 – Message length exceeds administrative limit
  • X.2.4 – Mailing list expansion issue

x.3.x Codes

  • X.3.0 – Other or undefined mail system status
  • X.3.1 – Mail system full
  • X.3.2 – System not accepting network messages
  • X.3.3 – System not capable of selected features
  • X.3.4 – Message too big for system
  • X.3.5 – System incorrectly configured

x.4.x Codes

  • X.4.0 – Other or undefined network or routing status
  • X.4.1 – No answer from host
  • X.4.2 – Bad connection
  • X.4.3 – Routing server failure
  • X.4.4 – Unable to route
  • X.4.5 – Network congestion
  • X.4.6 – Routing loop detected
  • X.4.7 – Delivery time expired

x.5.x Codes

  • X.5.0 – Other or undefined protocol status
  • X.5.1 – Invalid command
  • X.5.2 – Syntax error
  • X.5.3 – Too many recipients
  • X.5.4 – Invalid command arguments
  • X.5.5 – Wrong protocol version

x.6.x Codes

  • X.6.0 – Other or undefined media error
  • X.6.1 – Media not supported
  • X.6.2 – Conversion required and prohibited
  • X.6.3 – Conversion required but not supported
  • X.6.4 – Conversion with loss performed
  • X.6.5 – Conversion failed

x.7.x Codes

  • X.7.0 – Other or undefined security status
  • X.7.1 – Delivery not authorized, message refused
  • X.7.2 – Mailing list expansion prohibited
  • X.7.3 – Security conversion required but not possible
  • X.7.4 – Security features not supported
  • X.7.5 – Cryptographic failure
  • X.7.6 – Cryptographic algorithm not supported
  • X.7.7 – Message integrity failure
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