sending an email from a C/C++ program in linux

Question

I would like to send an email to my gmail account everytime my simulation ends. I have tried searching the web and found sendEmail but it is timing-out. If anyone could poin

Answer 1

I like the answer of trojanfoe above, BUT in my case I needed to turn on an email sending agent.. an MTA to enable linux to send emails - I have found exim4 to be a relatively simple MTA to get working and that trojanfoe's program works very nicely with it.

to get it to work I used (on a debian type system in a virtual box (crunchbang linux))

sudo apt-get install exim

sudo apt-get install mailutils

I configured exim4 with

sudo dpkg-reconfigure exim4-config

and I told the computer about my normal (remote) email address with

sudo emacs /etc/email-addresses

hope this might be useful as these were the steps I found worked to get my linux system sending email with trojanfoe's email program above

Answer 2

Both VMime and libcurl are good libraries for email sending (and more).

Answer 3

libESMTP seems to be what you are looking for. It's very well documented and also seems to be under active development (last Release Candidate is from mid-January 2012). It also supports SSL and various authentication protocols.

There are example applications in the source package.

Answer 4

Do a fork exec and pipe the body to a program like sendmail/mail:

#include <string>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>

using std::string;

static const int READEND = 0;
static const int WRITEEND = 1;

int sendEmail(const string& to, const string& subject, const string& body) {
  int p2cFd[2];

  int ret = pipe(p2cFd);
  if (ret) {
    return ret;
  }

  pid_t child_pid = fork();
  if (child_pid < 0) {
    close(p2cFd[READEND]);
    close(p2cFd[WRITEEND]);

    return child_pid;
  }
  else if (!child_pid) {
    dup2(p2cFd[READEND], READEND);
    close(p2cFd[READEND]);
    close(p2cFd[WRITEEND]);

    execlp("mail", "mail", "-s", subject.c_str(), to.c_str(), NULL);

    exit(EXIT_FAILURE);
  }

  close(p2cFd[READEND]);

  ret = write(p2cFd[WRITEEND], body.c_str(), body.size());
  if (ret < 0) {
    return ret;
  }

  close(p2cFd[WRITEEND]);

  if (waitpid(child_pid, &ret, 0) == -1) {
    return ret;
  }

  return 0;
}

int main() {
  return sendEmail("email@hostname.com", "Subject", "Body");
}

Answer 5

You could invoke your local MTA directly using popen() and feed it RFC822-compliant text.

#include <stdio.h>
#include <string.h>
#include <errno.h>
int sendmail(const char *to, const char *from, const char *subject, const char *message)
{
    int retval = -1;
    FILE *mailpipe = popen("/usr/lib/sendmail -t", "w");
    if (mailpipe != NULL) {
        fprintf(mailpipe, "To: %s\n", to);
        fprintf(mailpipe, "From: %s\n", from);
        fprintf(mailpipe, "Subject: %s\n\n", subject);
        fwrite(message, 1, strlen(message), mailpipe);
        fwrite(".\n", 1, 2, mailpipe);
        pclose(mailpipe);
        retval = 0;
     }
     else {
         perror("Failed to invoke sendmail");
     }
     return retval;
}

main(int argc, char** argv)
{
    int i;

    printf("argc = %d\n", argc);

    for (i = 0; i < argc; i++)
        printf("argv[%d] = \"%s\"\n", i, argv[i]);
    sendmail(argv[1], argv[2], argv[3], argv[4]);
}