Notice of dishonour of cheque by RPAD or by courier service or even by FAX is only meant to ascertain and ensure he service of notice . No since the bank has send you notice on your proper Email address and you have also acknowledge the same, it would be deemed as proper service of Notice and as such you cannot escape the liabiliy. RPAD notice may follow, however it is upto the court whether it takes complaint on the basis of such notice.