hello, yes this is possible and is exactly how i migrated to win2k recently. a new win2k domain with ex2000 on a dc, with a two-trust to the old domain and adc connecting ex2000 to ex5.5 in the same exchange site across the 2 domains. regards charles -----Original Message----- From: Jared Johnson [mailto:JaredsJazz@xxxxxxxxx] Sent: Sun 02/03/2003 23:56 To: [ExchangeList] Cc: Subject: [exchangelist] keep Exchange 5.5 running both... Does anyone know if you can keep an Exchange 5.5 machine running and working on an existing NT 4.0 network, while also having the ADC connected and running/servicing my new W2K domain at the same time?