Fax SMTP – Reference Appendix B: Error Conditions
This page explains how to deal with errors received when sending faxes automatically using our fax SMTP gateway.
The InterFAX service is a hybrid mail/fax server and will issue error messages within the SMTP communication stream, where possible. This provides a standard error-notification mechanism which captures errors, such as unidentified senders or malformed destination addresses, which may be returned immediately to the sender encapsulated as an email error condition.
For a definition of error codes see Interfax Error Codes.