(C++) 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 <CkEmail.h>

void ChilkatSample(void)
    {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // 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;

    const char *recipient = "admin@chilkatsoft.com";

    // Do a DNS MX lookup for the recipient's mail server.
    const char *smtpHostname = 0;
    smtpHostname = mailman.mxLookup(recipient);
    if (mailman.get_LastMethodSuccess() != true) {
        std::cout << mailman.lastErrorText() << "\r\n";
        return;
    }

    std::cout << smtpHostname << "\r\n";

    // 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("My Name <myname@mydomain.com>");
    email.AddTo("",recipient);

    bool success = mailman.SendEmail(email);
    if (success != true) {
        std::cout << mailman.lastErrorText() << "\r\n";
    }
    else {
        std::cout << "Mail Sent!" << "\r\n";
    }
    }