(Java) Verify Email Recipients

A way to possibly determine valid/invalid email addresses. I would recommend being very careful about doing this because your IP address may be flagged as a potential spammer by the mail server (because you are probing for valid/invalid email addresses). This Chilkat functionality existed for many years, before this kind of activity became a problem. The functionality remains only because it is useful for some to test with their own SMTP servers.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkMailMan mailman = new CkMailMan();

    // SMTP connection settings...
    mailman.put_SmtpHost("smtp.example.com");
    mailman.put_SmtpUsername("MY_SMTP_USERNAME");
    mailman.put_SmtpPassword("MY_SMTP_PASSWORD");
    mailman.put_SmtpSsl(true);
    mailman.put_SmtpPort(465);

    // Create a new email object
    CkEmail email = new CkEmail();

    email.put_Subject("This is a test");
    email.put_Body("This is a test");
    email.put_From("myemail@example.com");
    boolean success = email.AddTo("person1","person1@example.com");
    success = email.AddTo("person2","person2@example.com");
    success = email.AddTo("person3","person3@example.com");
    // The SMTP server smtp.example.com won't know anything about an email address @somewhere_else.com
    success = email.AddTo("person3","person4@somewhere_else.com");
    // ...

    // Verify recipients.
    // **** See the warning about using this API method in the description above.
    // (An SMTP server only knows valid email address for its own domain.  For example,
    // smtp.example.com *may* only know if person1@example.com is valid or invalid, but does
    // not know anything about the validity of email addresses having other domains.)
    CkStringArray badAddrs = new CkStringArray();
    success = mailman.VerifyRecips(email,badAddrs);
    if (success != true) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    int i = 0;
    while (i < badAddrs.get_Count()) {
        System.out.println(badAddrs.getString(i));
        i = i+1;
        }

    System.out.println("done.");
  }
}