Swift

Add a Custom Header Field to an Email

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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Swift


func chilkatTest() {
    //  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.

    let email = CkoEmail()!
    email.subject = "Custom header example"
    email.from = "alice@example.com"

    //  Add a custom header field.
    email.addHeaderField(fieldName: "X-Custom-Header", fieldValue: "custom value")

    print("X-Custom-Header = \(email.getHeaderField(fieldName: "X-Custom-Header")!)")

}