POPcon v3.00 and later includes a built-in "Re-route email to unknown recipients" feature. When enabled, emails addressed to users who are not found in Exchange/Active Directory are redirected to the configured postmaster or administrator address.
To enable
In POPcon's POP3/IMAP account configuration, enable the option "Re-route email to unknown recipients to postmaster" and verify that a valid postmaster email address is set on the General configuration tab.