https://evren-yurtesen.blogspot.com/2018/04/qmail-spp-plugin-for-getting-more.html
1. whois
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
int main(int argc, char **argv) {
char *user = getenv("SMTPAUTHUSER");
char *ip = getenv("TCPREMOTEIP");
char *mailfrom = getenv("SMTPMAILFROM");
char *rcptto = getenv("SMTPRCPTTO");
char *tempcount = getenv("SMTPRCPTCOUNTALL");
int rcptcount = atoi(tempcount);
int ppid = getppid();
if (user != NULL && strlen(user) > 0 && rcptcount < 2) {
fprintf(stderr, "auth: pid: %d ip: %s user: %s\n", ppid, ip, user);
}
fprintf(stderr, "info: pid: %d ip: %s from: %s to: %s count: %d\n", ppid, ip, mailfrom, rcptto, rcptcount);
return 0;