Sendmail 8.13.3 Programmer's Guide

Milter APIs
Callbacks
Chapter 238
The xxfi_envfrom() Callback
The xxfi_envfrom() callback handles the envelope FROM command.
xxfi_envfrom() returns the SMFIS_CONTINUE value to the calling filter
application. xxfi_envfrom() is called once during the beginning of each
message and before calling the xxfi_envrcpt() callback.
The declaration of xxfi_envfrom() is as follows:
#include <libmilter/mfapi.h>
sfsistat (*xxfi_envfrom)(
SMFICTX * ctx,
char **argv
);
Arguments
You must call xxfi_envfrom() with the following arguments:
ctx Specifies an opaque context structure.
argv Specifies null-terminated SMTP command arguments.
argv[0] denotes the address of the sender. Later
arguments, such as argv[1], argv[2], denote ESMTP
arguments.
For more information on ESTMP responses, see RFC
1869 (SMTP Service Extensions).
Return Values
xxfi_envfrom() returns the following values:
SMFIS_TEMPFAIL Rejects the sender and message with a temporary
error. The filter application does not call the
xxfi_abort() callback to abort the message and
you can specify a subsequent new message.
SMFIS_REJECT Rejects the sender and message. The filter
application does not call the xxfi_abort()
callback to abort the message and you can specify
a subsequent new message.
SMFIS_DISCARD Accepts and silently discards a message. The filter
application does not call the xxfi_abort()
callback to abort the message.