A client wanted to ensure their scripts were sending out mails without the clients actually receiving the mails and having them redirected somewhere else.
You can do this with an exim filter:
1. Create /etc/cpanel_exim_system_filter_custom with the following content:
# Stop outgoing emails and redirect
and (“$h_from:” contains “firstname.lastname@example.org”)
seen deliver “email@example.com”
Then in whm->Exim Configuration Editor->Filters
Change the filter to point to this new file.