privacy - Send email with specific email address linked to user real one and process replies (simply email redirect) -

i need send emails web-app users "from" field "19wds9w191dw98asxa91231as@my-site.com". if email receiver reply on message must delivered real email address of user system ("19wds9w191dw98asxa91231as@my-site.com" associated user email, "john.chavis@mail.com" example). email receiver never see original from email.

the same email conversation implemented, example, on booking.com.

how can that? gmail api (create aliases or else)? sendmail redirects? thanks!