(C#) Email BCC Recipients

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Explains the meaning of BCC recipients, how it is different than CC recipients, and how Chilkat handles BCC.

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// In the context of email communication, the BCC (Blind Carbon Copy) field is used to send a copy of an email
// to recipients without revealing their addresses to other recipients. When it comes to the MIME
// header of an email, the BCC email addresses should not be included.
// 
// The MIME header is a part of an email message that contains metadata and other information about the email,
// such as the sender, recipient(s), subject, and other details. However, the BCC field is meant to be a confidential field,
// and its purpose is to hide the recipients email addresses from each other.
// 
// Including BCC email addresses in the MIME header would defeat the purpose of using BCC since it would expose
// the hidden recipients addresses to the other recipients. This violates the intended privacy and confidentiality of the BCC feature.
// 
// To maintain the confidentiality of BCC recipients, the BCC field should only be used in the envelope of
// the email during the SMTP (Simple Mail Transfer Protocol) transaction. The SMTP server handles the actual
// delivery of the email to the respective recipients while keeping the BCC information hidden from other recipients.
// 
// It is important to ensure that BCC email addresses are not included in the MIME header of an email to
// preserve the privacy and confidentiality of the recipients.

// -----------------------------------------------------------------------------------------
// To discuss how Chilkat handles BCC, let's first create an email with some BCC recipients.
Chilkat.Email email = new Chilkat.Email();

email.AddTo("Joe","joe@example.com");
email.AddTo("Mary","mary@example.com");
email.AddCC("Steve","steve@example.com");
email.AddBcc("Jerry","jerry@example.com");
email.AddBcc("Tom","tom@example.com");

email.Subject = "test";
email.Body = "test";

// Let's examine the MIME
Debug.WriteLine(email.GetMime());
Debug.WriteLine("----------------");

// We have the following.
// Notice the BCC addresses are not present.  They are not included in the MIME header.

// MIME-Version: 1.0
// Date: Mon, 10 Jul 2023 13:57:22 -0500
// Message-ID: <34606FFCB4A440B20E549A223F2F7BF0EB10EE2C@SLICE>
// Content-Type: text/plain; charset=us-ascii; format=flowed
// Content-Transfer-Encoding: 7bit
// X-Priority: 3 (Normal)
// To: Joe <joe@example.com>, Mary <mary@example.com>
// Cc: Steve <steve@example.com>
// Subject: test
// 
// test

// However the BCC address are still stored in the Chilkat email object.
// For example, you can examine the BCC recipients in the email object like this:
int numBcc = email.NumBcc;
Debug.WriteLine("Num BCC recipients = " + Convert.ToString(numBcc));

int i = 0;
while (i < numBcc) {
    Debug.WriteLine(Convert.ToString(i));
    Debug.WriteLine(email.GetBcc(i));
    Debug.WriteLine(email.GetBccName(i));
    Debug.WriteLine(email.GetBccAddr(i));
    Debug.WriteLine("-----");
    i = i + 1;
}

// Output:

// Num BCC recipients = 2
// 0
// Jerry <jerry@example.com>
// Jerry
// jerry@example.com
// -----
// 1
// Tom <tom@example.com>
// Tom
// tom@example.com
// -----

// Thus, when the email is sent, it will also be sent to the BCC recipients,
// but the email received by each of the recipients (i.e. the raw MIME of the email) 
// should not and will not include the BCC email addresses.  There should be no way
// for the recipients to know that the email was sent to the BCC addresses -- because if 
// there is a way to know, then it is not truly BCC.