code: func NewMailTarget() *MailTarget {
  	return &MailTarget{
  		Filter:     &Filter{MaxLevel: LevelDebug},
  		BufferSize: 1024,
  		close:      make(chan bool, 0),
  	}
  }
docs: // NewMailTarget creates a MailTarget.
  // The new MailTarget takes these default options:
  // MaxLevel: LevelDebug, BufferSize: 1024.
  // You must specify these fields: Host, Username, Subject, Sender, and Recipients.