Send Email without Mail Server

How to send an email without a mail server (so-to-speak).

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#include <CkMailMan.h>
#include <CkString.h>
#include <CkEmail.h>

void ChilkatSample(void)
    {

    //  Is it really possible to send email without connecting to
    //  a mail server?  Not really.

    //  When people ask 'Do you support sending email without
    //  a mail server'?  what they're really asking is: 'I don't
    //  have an SMTP server, and I want to send email.  I see
    //  other components available where it's not necessary
    //  to specify an SMTP server.  Does your component have that
    //  ability?'  In short, the answer is Yes.  But you need
    //  to understand some things before you jump in...

    //  Here's what happens inside those other components
    //  that claim to not need a mail server:  The component does
    //  a DNS MX lookup using the intended recipient's email address
    //  to find the mail server (i.e. SMTP server) for that
    //  domain.  It then connects to that server and delivers the
    //  email.  You're still connecting to an SMTP server -- just
    //  not YOUR server.

    //  Chilkat provides an MxLookup method where you can lookup
    //  the SMTP hostname that services any given email address.
    //  You would then assign the SmtpHost property to this value.
    //  Chilkat can then connect directly to the recipient's mail
    //  server and deliver the email.

    //  There are a few gotcha's though...

    //  First, if you're writing an application that is widely
    //  distributed, your app might be running within a network
    //  that blocks outgoing connections to the SMTP port.
    //  Earthlink, for example, is one major ISP that does this.
    //  When you are connected to the Internet via Earthlink,
    //  your apps can *only* connect to Earthlink's SMTP server
    //  and will not be able to reach any remote servers.  To send
    //  email, you must use Earthlink's SMTP as a relay.  This is
    //  common with ISPs.  So... if your application is coded
    //  as in this example, it will not work within those networks.
    // 
    //  Second, some SMTP servers will reject unauthenticated
    //  sessions attempting to send email from dynamic IP addresses.
    //  You may see this error in your LastErrorText:
    //  553-Your attempt to send email to us has been blocked
    //  553-because your email server is not currently on that domain's Accepted
    //  553-Senders list. To request addition to their Accepted Senders list,
    //  553-please navigate with a Web browser to the following URL:
    //  553-http://reportrbl.gate2service.com/Whitelist/?IPAddress=67.173.123.150
    //  553 See http://www.dnsbl.us.sorbs.net/ (dul)

    //  In a nutshell, just because you were able to do the MxLookup
    //  and connect to the recipient's mail server, doesn't mean
    //  you'll be able to send email -- it depends on the IP address
    //  from which you're connecting.

    //  Finally, the DNS lookup is potentially time consuming.
    //  In addition, you cannot use somebody else's email server
    //  as a relay, so if you're connecting to smtp.xyz.com, you
    //  can only send email to email addresses at xyz.com.
    //  To send email to 3 recipients at different domains means
    //  making 3 separate connections to 3 separate SMTP servers
    //  to send the email one at a time.

    //  The mailman object is used for sending and receiving email.
    CkMailMan mailman;

    //  Any string argument automatically begins the 30-day trial.
    bool success;
    success = mailman.UnlockComponent("30-day trial");
    if (success != true) {
        printf("Component unlock failed\n");
        return;
    }

    CkString recipient;
    recipient = "admin@chilkatsoft.com";

    //  Do a DNS MX lookup for the recipient's mail server.
    CkString smtpHostname;
    smtpHostname = mailman.mxLookup(recipient);
    if (smtpHostname.getNumChars() == 0 ) {
        printf("%s\n",mailman.lastErrorText());
        return;
    }

    printf("%s\n",(const char *)smtpHostname);

    //  Set the SMTP server.
    mailman.put_SmtpHost(smtpHostname);

    //  Create a new email object
    CkEmail email;

    email.put_Subject("This is a test");
    email.put_Body("This is a test");
    email.put_From("Chilkat Support <support@chilkatsoft.com>");
    email.AddTo("",recipient);

    success = mailman.SendEmail(email);
    if (success != true) {
        printf("%s\n",mailman.lastErrorText());
    }
    else {
        printf("Mail Sent!\n");
    }

    }