[petree]

wow, thank you for this very quick reply.

I want to receive e-mails on both server and to have users sync on them.
and in case that the first one goes down users could work with the second srv.

on second server: mail2.mydomain.com

cat /etc/hosts
127.0.0.1 localhost
192.168.105.101 mail2.mydomain.com mail2

cat /etc/bind/db.mydomain.com
;
; Addresses and other host information.
;
@ IN SOA mydomain.com. admin.mydomain.com. (
10124 ; Serial
43200 ; Refresh
3600 ; Retry
3600000 ; Expire
2592000 ) ; Minimum
; Define the nameservers and the mail servers
IN NS 192.168.105.101
IN A 192.168.105.100
IN A 192.168.105.101
mail2.mydomain.com. IN MX 0 mail2.mydomain.com.
IN MX 0 mail2.mydomain.com.
IN MX 0 mydomain.com.
mail2 IN A 192.168.105.101
mydomain.com IN A 192.168.105.100

the first server's hostname is mydomain.com
the second: mail2.mydomain.com

thank you