code: func (m *MailYak) AttachInlineWithMimeType(name string, r io.Reader, mimeType string) {
  	m.attachments = append(m.attachments, attachment{
  		filename: name,
  		content:  r,
  		inline:   true,
  		mimeType: mimeType,
  	})
  }
docs: // AttachInlineWithMimeType adds the contents of r to the email as an inline attachment
  // with mimeType as the specified MIME type of the content. Inline attachments are
  // typically used within the email body, such as a logo or header image. It is up to the
  // user to ensure name is unique and the specified mimeType is correct.
  //
  // Files can be referenced by their name within the email using the cid URL
  // protocol:
  //
  // 		<img src="cid:myFileName"/>
  //
  // r is not read until Send is called.