Hi prudens,
As I understand it, you would like to know whether there is a way to specify the recipient when auto replying the “A is on behalf of B” emails.
Actually, when auto replying any “A is on behalf of B” emails, the mails will deliver to recipient B. Currently, it is not available to specify another recipient rather than B.
However, as to the feature you discussed here, to make it better meet your requirements, I invite you to submit your feedback for the further improving of our products. To make the suggestions better understood, please provide your detailed description on what you’d like to improve. This will make the feedback more useful for the relevant teams. You can submit your feedback at http://g.microsoftonline.com/0BX11EN/135 .
If the service is requested frequently, the product team may include it in future product releases. Your efforts on working closely to improve our products are highly appreciated.
Thanks,
Maggie Li