mail/message.go
func (m *Message) AddBodies(data render.Data, renderers ...render.Renderer) error {
	for _, r := range renderers {
		err := m.AddBody(r, data)
		if err != nil {
			return err
		}
	}

	return nil
}
func (m *Message) AddBodies(data render.Data, renderers ...render.Renderer) error {
	for _, r := range renderers {
		err := m.AddBody(r, data)
		if err != nil {
			return err
		}
	}

	return nil
}
// AddBodies Allows to add multiple bodies to the message, it returns errors that
// could happen in the rendering.