Support test: Problem solving

Task: You receive the following mail, how do you approach the problem?

 Hello

 I have a problem with the share by mail function.
 Some of my partners dont receive mail sent with this function, because their mail solution block mails with not real domain name.
 Sender of mail sent by the share function are made with the component : noreply@hostname.domain.
 But our domain is an intranet domain, not available on the web, so many mail filter system block this.

 Is their a way to change the send for this function?
 Note that the email settings are good on the administration page.