VB.NET

Add a Custom Header to an Email Attachment

Demonstrates the Chilkat Email.AddAttachmentHeader method, which adds a custom MIME header field to an existing attachment identified by its zero-based index. This example adds an attachment (which becomes index 0), then attaches an extra header field to it and prints the resulting MIME.

Background: In MIME, every attachment is itself a mini-message with its own small block of headers — things like Content-Type, Content-Disposition, and Content-Transfer-Encoding that describe that specific part. AddAttachmentHeader lets you insert additional fields into that per-part header block, which is occasionally needed for interoperability with systems that look for custom X- headers or content identifiers on individual attachments.

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VB.NET

'  Demonstrates the AddAttachmentHeader method, which adds a custom MIME header field to
'  an existing attachment, identified by its zero-based index.

Dim email As New Chilkat.Email
email.Subject = "Attachment with a custom header"
email.Body = "The attachment has an extra MIME header."

'  Add an attachment; it becomes attachment index 0.
email.AddStringAttachment("data.txt","Attachment body.")

'  Add a custom header field to the first attachment (index 0).
email.AddAttachmentHeader(0,"X-Custom-Attachment-Header","some value")

'  The custom header now appears in the attachment's MIME part.
Debug.WriteLine(email.GetMime())