Hi Ben, You need to setup MX records with different priorities for both domains pointing to both servers so that one server is the backup for the other. The DNS server in one of the domains must have: MX 10 domain1 server1 MX 20 domain1 server2 On the other DNS server you must have: MX 10 domain2 server2 MX 20 domain2 server1 Then you must configure the SMTP connector on both servers to issue the ETRN command to retrieve messages for its own domain that might be stored in the other server. The ETRN configuration itself depends if you are running Exchange 5.5 or Exchange 2000. Regards Alberto Boczar att/PS Informatica S.A. Brazil http://www.attps.com.br * (31) 3298-4740 * aboczar@xxxxxxxxxxxx -----Original Message----- From: Ben Nichols [mailto:Ben@xxxxxxxxxxxxxxxxxxxx] Sent: terca-feira, 18 de setembro de 2001 11:59 To: [ISAserver.org Discussion List] Subject: Exchange Backup Hello, This is slightly off topic I know, but generally you guys are so helpful... I have 2 win2k networks both at separate locations with separate win2k domains. I am running exchange and isa on each. Occasionally one of the 2 sites loses its internet connection (one has adsl, the other, cable modem). At the moment each of them are backup dns servers for each other. I would like to setup a similar arrangement with exchange, whereby if one site goes down, the other site will accept mail for it and when it comes back online forward all mail on. I understand MX records etc as we currently have a linux setup working happily. Can anyone please point me in the right direction with setting up exchange on the 2 servers? Many thanks, Ben