That isn't how email confirmation works, because it's a) enormously prone to false negatives, b) subject to ruinous delays, c) occurring after the transaction i

That isn't how email confirmation works, because it's a) enormously prone to false negatives, b) subject to ruinous delays, c) occurring after the transaction i.e. too late, and d) building you a reputation as a bad sender. This is why all email address confirmation today is asking you to click a link or enter a code. Also note that the latter strategy is rising in popularity; it is because clickable links, whilst seeming so convenient, are themselves prone to both false positives and negatives, and also increase the likelihood of ending up in junk mail.