Excel Macro To Copy Data From One Sheet To Multiple Sheets Without Duplications

We have a company and need to automating workflow.

The Master sheet contains incoming mail details by customer. Each employee is assigned a set number of customers to respond to. We want the information on the Master sheet to filter to a specific employee assigned sheet. On the employee assigned sheet, once filtered, they are to provide updates in column E

Date
Reference no.
Name
Employee ID
16-Feb-12
S/S/1

[Code] ........

We need a macro that can filter customers' details to the specific employee assigned sheet based on the employee ID in the master sheet. For example, all customers assigned to DW (i.e with the 'DW' employee ID) filters into a sheet called 'DW'. Please note that the Master sheet is a continuous log updated daily. This macro must not duplicate information previously filtered once the employee enters a status update in column E.