thanks.
我睇返原來一定要用
apt-get -f install

install 果個字之後一定要冇野先得.

再家 ok 啦

Step 如下

#1 Problem here
dfserver:~# apt-get install postfix
Reading package lists... Done
Building dependency tree... Done
You might want to run `apt-get -f install' to correct these:
The following packages have unmet dependencies:
exim4-config: Conflicts: postfix but 2.2.10-2 is to be installed
exim4-daemon-light: Conflicts: mail-transport-agent
linux-image-2.6.12-1-386: Depends: initrd-tools (>= 0.1.78) but it is not going to be installed
postfix: Depends: libc6 (>= 2.3.6-6) but 2.3.5-6 is to be installed
Depends: libsasl2 (>= 2.1.19.dfsg1) but 2.1.19-1.7 is to be installed
Depends: libssl0.9.8 (>= 0.9.8b-1) but 0.9.8a-3 is to be installed
Conflicts: mail-transport-agent
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

#2 Solution here, use apt-get -f install
dfserver:~# apt-get -f install
Reading package lists... Done
Building dependency tree... Done
Correcting dependencies... Done
The following extra packages will be installed:
initrd-tools
The following NEW packages will be installed:
initrd-tools
0 upgraded, 1 newly installed, 0 to remove and 512 not upgraded.
Need to get 32.1kB of archives.
After unpacking 184kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Get:1 ftp://ftp.hk.debian.org testing/main initrd-tools 0.1.84.1 [32.1kB]
Fetched 32.1kB in 0s (36.1kB/s)
Selecting previously deselected package initrd-tools.
(Reading database ... 62745 files and directories currently installed.)
Unpacking initrd-tools (from .../initrd-tools_0.1.84.1_all.deb) ...
Setting up initrd-tools (0.1.84.1) ...

Configuration file `/etc/mkinitrd/mkinitrd.conf'
==> Modified (by you or by a script) since installation.
==> Package distributor has shipped an updated version.
What would you like to do about it ? Your options are:
Y or I : install the package maintainer's version
N or O : keep your currently-installed version
D : show the differences between the versions
Z : background this process to examine the situation
The default action is to keep your current version.
*** mkinitrd.conf (Y/I/N/O/D/Z) [default=N] ?

#3 Start installing postfix again. The dependency problem has gone.
dfserver:~# apt-get install postfix
Reading package lists... Done
Building dependency tree... Done
The following extra packages will be installed:
libc6 libc6-dev libgnutls13 libgpg-error0 libopencdk8 libsasl2 libssl0.9.8 libtasn1-3 openssl
Suggested packages:
glibc-doc gnutls-bin postfix-mysql postfix-pgsql postfix-ldap postfix-pcre sasl2-bin
Recommended packages:
libsasl2-modules libtasn1-3-bin resolvconf
The following packages will be REMOVED:
exim4 exim4-base exim4-config exim4-daemon-light
The following NEW packages will be installed:
libgnutls13 libtasn1-3 postfix
The following packages will be upgraded:
libc6 libc6-dev libgpg-error0 libopencdk8 libsasl2 libssl0.9.8 openssl
7 upgraded, 3 newly installed, 4 to remove and 501 not upgraded.
Need to get 0B/12.8MB of archives.
After unpacking 5222kB disk space will be freed.
Do you want to continue [Y/n]? y
Preconfiguring packages ...
(Reading database ... 62758 files and directories currently installed.)
Removing exim4 ...
dpkg: exim4-base: dependency problems, but removing anyway as you request:
exim4-daemon-light depends on exim4-base (>= 4.54).
Removing exim4-base ...
Stopping MTA: exim4.
Removing exim4-config ...
dpkg: exim4-daemon-light: dependency problems, but removing anyway as you request:
at depends on mail-transport-agent; however:
Package mail-transport-agent is not installed.
Package exim4-daemon-light which provides mail-transport-agent is to be removed.
mailx depends on exim4 | mail-transport-agent; however:
Package exim4 is not installed.
Package mail-transport-agent is not installed.
Package exim4-daemon-light which provides mail-transport-agent is to be removed.
mutt depends on exim4 | mail-transport-agent; however:
Package exim4 is not installed.
Package mail-transport-agent is not installed.
Package exim4-daemon-light which provides mail-transport-agent is to be removed.
Removing exim4-daemon-light ...
Stopping MTA: exim4.
(Reading database ... 62640 files and directories currently installed.)
Preparing to replace libc6-dev 2.3.5-6 (using .../libc6-dev_2.3.6-15_i386.deb) ...
Unpacking replacement libc6-dev ...
Preparing to replace libc6 2.3.5-6 (using .../libc6_2.3.6-15_i386.deb) ...
Unpacking replacement libc6 ...
Setting up libc6 (2.3.6-15) ...
Installing new version of config file /etc/init.d/glibc.sh ...

(Reading database ... 62651 files and directories currently installed.)
Preparing to replace libgpg-error0 1.1-4 (using .../libgpg-error0_1.2-1_i386.deb) ...
Unpacking replacement libgpg-error0 ...
Preparing to replace libopencdk8 0.5.7-2 (using .../libopencdk8_0.5.8-1_i386.deb) ...
Unpacking replacement libopencdk8 ...
Selecting previously deselected package libtasn1-3.
Unpacking libtasn1-3 (from .../libtasn1-3_0.3.5-1_i386.deb) ...
Selecting previously deselected package libgnutls13.
Unpacking libgnutls13 (from .../libgnutls13_1.4.1-1_i386.deb) ...
Preparing to replace libsasl2 2.1.19-1.7 (using .../libsasl2_2.1.19.dfsg1-0.2_i386.deb) ...
Unpacking replacement libsasl2 ...
Preparing to replace openssl 0.9.8a-3 (using .../openssl_0.9.8b-2_i386.deb) ...
Unpacking replacement openssl ...
Preparing to replace libssl0.9.8 0.9.8a-3 (using .../libssl0.9.8_0.9.8b-2_i386.deb) ...
Unpacking replacement libssl0.9.8 ...
Selecting previously deselected package postfix.
Unpacking postfix (from .../postfix_2.2.10-2_i386.deb) ...
Setting up libc6-dev (2.3.6-15) ...
Setting up libgpg-error0 (1.2-1) ...

Setting up libopencdk8 (0.5.8-1) ...

Setting up libtasn1-3 (0.3.5-1) ...

Setting up libgnutls13 (1.4.1-1) ...

Setting up libsasl2 (2.1.19.dfsg1-0.2) ...

Setting up libssl0.9.8 (0.9.8b-2) ...

Setting up openssl (0.9.8b-2) ...

Setting up postfix (2.2.10-2) ...
Adding group `postfix' (108)...
Done.
Adding system user `postfix'...
Adding new user `postfix' (106) with group `postfix'.
Not creating home directory `/var/spool/postfix'.
setting synchronous mail queue updates: true
Creating /etc/postfix/dynamicmaps.cf
Adding tcp map entry to /etc/postfix/dynamicmaps.cf
Adding group `postdrop' (109)...
Done.
setting myhostname: dfserver
setting alias maps
setting alias database
mailname is not a fully qualified domain name. Not changing /etc/mailname.
setting destinations: dfserver, localhost.localdomain, , localhost, dragonfast.com, hzportint.com, hypercubeinc.com, dfast.erickwok.com, dfast.dyndns.org
setting relayhost:
setting mynetworks: 127.0.0.0/8
setting mailbox_command
setting mailbox_size_limit: 0
setting recipient_delimiter: +
setting inet_interfaces: all

Postfix is now set up with a default configuration. If you need to make
changes, edit
/etc/postfix/main.cf (and others) as needed. To view Postfix configuration
values, see postconf(1).

After modifying main.cf, be sure to run '/etc/init.d/postfix reload'.

Running newaliases
Stopping Postfix Mail Transport Agent: postfix.
Starting Postfix Mail Transport Agent: postfix.

dfserver:~#