SRM Offline Approval Issue

Hi,

I am testing Confirmation/shopping cart/Invoice Offlline approval fesibility testing

I am able to generate wokrflow mail in outlook for Approve or Reject

in Outlook when I am clicking Approve or Reject it is generating one more response email in outlook with some link in mail

and when I am clinking on send the email Id which generating at the time of clicking on approve or Reject bouncing back

Please let me know ..

1) Do I need to maintain that email Id somewhere in SRM system OR

2) Some where in SMTP exchage server of Outlook

I have compared the Production Email Id and it is working fine and my IT team checked that PRD email Id also not maintained in the SMTP server, not sure where we are missing.

Please help.

Thanks,

Jai