Mail filter callbacks

Each of these callbacks should return one of the values that is defined in Table 1. Any value other than those listed constitutes an error and causes sendmail to terminate its connection to the offending filter.

Table 1. Callback return values
Return value	Description
SMFIS_CONTINUE	Continue processing the current connection, message, or recipient.
SMFIS_REJECT	For a connection-oriented routine, reject this connection; call xxfi_close. For a message-oriented routine (except xxfi_eom or xxfi_abort), reject this message. For a recipient-oriented routine, reject the current recipient (but continue processing the current message).
SMFIS_DISCARD	For a message or recipient-oriented routine, accept this message, but silently discard it. SMFIS_DISCARD should not be returned by a connection-oriented routine.
SMFIS_ACCEPT	For a connection-oriented routine, accept this connection without further filter processing; call xxfi_close. For a message or recipient-oriented routine, accept this message without further filtering.
SMFIS_TEMPFAIL	Return a temporary failure; the corresponding SMTP command will return an appropriate 4xx status code. For a message-oriented routine (except xxfi_envfrom), fail for this message. For a connection-oriented routine, fail for this connection; call xxfi_close. For a recipient-oriented routine, fail only for the current recipient; continue message processing.