[Mail] send mails to bcc

pkg/mailer/mailer.go

@@ -32,7 +32,7 @@ func NewMessageFrom(to []string, from, subject, htmlBody string) *Message {
 
 	msg := gomail.NewMessage()
 	msg.SetHeader("From", from)
-	msg.SetHeader("To", to...)
+	msg.SetHeader("Bcc", to...)
 	msg.SetHeader("Subject", subject)
 	msg.SetDateHeader("Date", time.Now())