Domain email address on an external pc

As a (very) novice small business admin on a Server 2003 network (with Exchange) I am stuck on how to set up my pre-existing domain email address on the system so that other local users can email me at home using this (longstanding and widely known) address. In other words I use my domain email address on a laptop at home but other network users can’t email me without the email being retained on the network until I log in (at work) it. External non-network email gets through ok, just none from my network users at work.