Reply to info in delegated mail

When the owner uses the mail file to send internet mail, the reply-to address shown to the recipient is the one specified in the Location Document for the user.

When a delegated user uses the mail file to send internet mail the reply-to and sender address shows as example:

John_Smith/ddnd@domain.com

The delegate is shown in the Mail App as

John Smith/ddnd

I’m sure I am missing something in a setting. Can’t imagine that this is the normal way it would work.

Any help would be very appreciated as this is really annoying and looks bad to the “public”.