Add a Custom Header Field to an Email

See more Email Object Examples

Demonstrates the Chilkat Email.AddHeaderField method, which adds a standard or custom header field. If the field already exists, this method replaces it (use AddHeaderField2 to allow duplicates). Header fields whose names begin with CKX- are not transmitted when the email is sent, but are preserved across XML save/load, making them handy for persistent metadata. This example adds a custom X- header and reads it back.

Background: Beyond the well-known headers (From, Subject, etc.), MIME lets you add arbitrary fields. By convention custom, non-standard fields are prefixed with X-, so mail systems know not to expect them in the standards. Applications use these to carry tracking IDs, campaign tags, or routing hints. Chilkat's CKX- convention goes a step further — those fields live with the object but are stripped before the message is actually sent.

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#include <C_CkEmail.h>

void ChilkatSample(void)
    {
    HCkEmail email;

    //  Demonstrates the AddHeaderField method, which adds a standard or custom header field.
    //  If the header field already exists, this method REPLACES it.  (To allow duplicates,
    //  use AddHeaderField2 instead.)  Header fields whose names begin with "CKX-" are not
    //  transmitted when the email is sent, but are preserved when saved to/loaded from XML.

    email = CkEmail_Create();
    CkEmail_putSubject(email,"Custom header example");
    CkEmail_putFrom(email,"alice@example.com");

    //  Add a custom header field.
    CkEmail_AddHeaderField(email,"X-Custom-Header","custom value");

    printf("X-Custom-Header = %s\n",CkEmail_getHeaderField(email,"X-Custom-Header"));


    CkEmail_Dispose(email);

    }