How to use a Group Distribution list inorder to send and received messages

I did a group distribution list in order to agroup some users. by example
group@xxxxxxxxxxx

and have some users members of this group
karen.lastname@xxxxxxxxxxx
example2@xxxxxxxxxxx


Now well, we need that when anyone send email to group distribution
group@xxxxxxxxxxx and anyone member of this group respond
(exapmple2@xxxxxxxxxxx) , the answer show sender group@xxxxxxxxxxx ,however
the answer were from example2@xxxxxxxxxxx

How to do that?

Thanks in advanced


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