mail/message.go
func (m *Message) AddEmbedded(name string, r io.Reader) error {
	m.Attachments = append(m.Attachments, Attachment{
		Name:     name,
		Reader:   r,
		Embedded: true,
	})

	return nil
}
func (m *Message) AddEmbedded(name string, r io.Reader) error {
	m.Attachments = append(m.Attachments, Attachment{
		Name:     name,
		Reader:   r,
		Embedded: true,
	})

	return nil
}
//AddEmbedded adds the attachment to the list of attachments
// the Message has and uses inline instead of attachement property.