You will need to set sendmail to point to where sendmail resides on your system
if it is different. 
To: will be the recipient of the Email
From: is who you wish to be displayed as the sender
Subject: is the subject you wish the email to have
Text: is the body of the email
Host: is a security measure so you can validate who sent what.
      It is recommend if you allow players to use this, you record their host
      for potential abuse tracking. Immortals as well. If no host is passed
      it will automatically assume the host is localhost.
Uncomment X-Abuse and add the appropriate address if you wish to be user friendly.


void sendmail( char *to, char *from, char *subject, char *text, char *host )
{
    FILE *fp;
    char *sendmail="/usr/lib/sendmail -i -t";

    if ((fp = popen( sendmail, "w" )) == NULL)
    {
      bug( "%s failed to open sendmail.", __FUNCTION__);
      return;
    }
    fprintf( fp, "To: %s\n", to);
    fprintf( fp, "From: %s\n", from);
    fprintf( fp, "X-Notice: This mail was generated by %s's internal mail system.\n", sysdata.mud_name);
//    fprintf( fp, "X-Abuse: Report abuse to admin @ %s\n", sysdata.mud_name);
    fprintf( fp, "X-Originating-Host: %s\n", host ? host : "127.0.0.1" );
    fprintf( fp, "Subject: %s\n\n", subject);

/* This is the text */
    fprintf( fp, "%s\n", text);
    pclose( fp );
    return;
}