mail/internal/mail/message.go
func (m *Message) AddAlternativeWriter(contentType string, f func(io.Writer) error, settings ...PartSetting) {
	m.parts = append(m.parts, m.newPart(contentType, f, settings))
}
func (m *Message) AddAlternativeWriter(contentType string, f func(io.Writer) error, settings ...PartSetting) {
	m.parts = append(m.parts, m.newPart(contentType, f, settings))
}
func ( m * Message ) AddAlternativeWriter ( contentType string , f func ( io . Writer ) error , settings ... PartSetting ) { m . parts = append ( m . parts , m . newPart ( contentType , f , settings ) ) }
// AddAlternativeWriter adds an alternative part to the message. It can be
// useful with the text/template or html/template packages.
AddAlternativeWriter adds an alternative part to the message . It can be useful with the text / template or html / template packages .