Hello, I do not know what is the default exists under ezpublis, or you can define a workflow, just after the publication of a new comment, you sending emails
but this is not my requirement i need a provision in my feedback form to add multiple receiver email id and i should be able to change that email id from my admin back end by editing that form object.
It would really depend on how this was implemented - whether or not someone put the functionality in an extension or not. But, if the feedback form is a standard information collector and this was implemented with a kernel hack then it is/was in kernel/content/collectinformation.php
What I've done (over and over) is to add something like this to the file (around line 290) near where the receiver(s) are set:
Of course if the attribute is a comma seperated text line then it would need some more code to do that.
Did this break after an upgrade? I'm guessing that during an upgrade the necessary hack wasn't migrated - check your old files or old revisions if you can.
If not, then see what the attribute identifier is (the 'recipient' in the above code) and search your (old) code for that.