Mailwasher can't bounce, Outlook can't bounce, not sure if Thunderbird can even bounce.
Horde can bounce and will save you physically downloading the email, however you can't send email from
info@xyz.com account on your server to
info@xyz.com account which is now elsehwere as I explained before, the server will not see the new account it'll just return the email back into the existing account on its own server.
For software, pocomail will bounce. You could probably get this running as a trial version and do what you need before the trial expires.
Alternatively, you'll need to use Horde on the client's site, bounce the email to one of your accounts on a different server (not domain but actual physical server) if you have one, and then bounce them again.
I hope the client is paying for all of this work you're supplying!
