|Bad destination mailbox address
|The specified email address does not exist. This means that the portion on the left of the @ is invalid.
|Bad destination system address
|The domain specified in the email address is unable to accept emails.
|Bad destination mailbox address syntax
|A syntactic problem has been detected by the receiving domain.
|Recipient Block Policy
|The receiving user has created (only at the level of his own mailbox) a personal filter that blocks the address or domain sender of the email.
|Bad sender’s mailbox address syntax
|The sender address was syntactically invalid.
|Bad sender’s system address
|The sender domain is unable to accept reply emails.
|Other or undefined mailbox status
|The mailbox was not able to accept emails.
|Mailbox disabled, not accepting messages
|The mailbox exists but is not accepting messages. This may be a temporary or permanent error.
|The user’s mailbox is full because its maximum capacity has been reached. You can clear it by deleting messages.
|Message length exceeds administrative limit
|An administrative limit in the message size has been exceeded. This error occurs when the size allowed by the recipient’s box is smaller than the generic system limit.
|Message rejected due to reputation problems of the sender IP address or domain, caused for example by its presence in public blacklists or blocks by antispam systems, of the email providers that return this type of bounce. A problem of this type is resolved as soon as the IP or domain is unblocked or de-listed, so this type of bounce does not cause the email address to be blacklisted.
|No answer from host
|The outbound connection attempt was not accepted either because the system was busy or because it was incapacitated.
|The outgoing connection was established but was unable to process the message, either because it went into time out or because of poor connection quality.
|Routing server failure
|The system was unable to forward the message due to unavailable directory servers (e.g., inability to connect to DNS server).
|Unable to route
|The system cannot find the correct path to the destination server. Sometimes it may also depend on the non-existence of the domain.
|Routing loop detected
|Mail servers check if the same message passes through them more than once and after the umpteenth time (at the discretion of the postmaster as always) they decide that the message will never reach its destination and send it back notifying the rejection.
|Delivery time expired
|Our system, in case of unreachability of the receiving mail server (without receiving specific rejection) performs multiple retries. If after 48 hours it is still not able to deliver the message it is considered failed and categorized as bounce. (the cause may be a server temporarily down or a domain with no MX records)
|Other or undefined protocol status
|An error occurred in the message transmission protocol
|An out-of-sequence or unsupported protocol command was entered.
|A protocol command was entered that cannot be interpreted because the syntax is incorrect or it was not recognized.
|Delivery not authorized, message refused
|The sender is not allowed to send to the specified recipient. The cause could be a blockage in the per-host or per-recipient spam filter.
|In a pass through the various servers, one of them could not deliver the email. The message is rejected by the server, it could be due to the sender being recognized as invalid or unacceptable
|Service not available – access denied
|Typically caused by incorrect or old email addresses; when trying to deliver mail to a server that is intended only to send mail and not to receive it. Sometimes used as a response when mail is rejected as spam.
|Message considered to be spam
|The message is considered spam
|Teleservice not provisioned
|Rejected by Operator
|Controlling MSC system failure
|Equipment protocol error
|System (Internal Error)
|ERROR (Internal Error)
|ERROR (Internal Error)
|Rejected – Nack
|Deleted – Canceled
|Expired, all the carrier attempts failed during the validity period
|Rejected from the destination carrier
|Subscriber not provisioned
|Handset memory exceeded
|Charging balance to low
|DB52 SMSC ERROR
|DB76 NO SERVICE
|DB99 PORTED NUMBER
|DB62 SMSC ERROR
|DB65 VP EXPIRED
|DB78 NO BALANCE
|DB05 SMSC ERROR
|4503 OUT OF COVERAGE
|Teleservice not provisioned
|Account limit is reached
|Max amount of messages reached
|MSISDN is blacklisted
|MSISDN or destination operator blacklisted
|Call barred by operator
|The operator has blocked the message. This is not a network error but an explicit answer from the operator platform. For example it can be received when the end user has reached is monthly/daily usage limit.
|Subscriber profile does not permit service
|This can be due to user explicitly requesting to be barred from Premium services (i.e. corporate mobile phone contracts).
|Unknown or Ported Number
|Unknown MSISDN or ported number.
|Failed Message Delivery
|Validity Period Expired
|The operator SMSC was not able to deliver the message within its Validity Period.
|Subscriber is temporarily out of credit
|End user has no credit.
|No operator found for current MSISDN
|No operator associated to this MSISDN. Check that MSISDN is correct.
|Undeliverable, destination doesn’t exists or has persistent problem.