Sure, the log is:
Installation started in background
Checking whether the package dependencies are resolved.
Installing packages
Reading package lists...
Building dependency tree...
Reading state information...
debhelper is already the newest version.
man-db is already the newest version.
Suggested packages:
procmail postfix-mysql postfix-pgsql postfix-ldap sasl2-bin dovecot-common
resolvconf postfix-cdb ufw postfix-doc
The following NEW packages will be installed:
plesk-mail-pc-driver postfix postfix-pcre
0 upgraded, 3 newly installed, 0 to remove and 1 not upgraded.
2 not fully installed or removed.
Need to get 2833 kB/4424 kB of archives.
After this operation, 10.4 MB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
postfix postfix-pcre plesk-mail-pc-driver
Authentication warning overridden.
Get:1
http://mirror.hetzner.de/debian/packages/ wheezy/main postfix-pcre amd64 2.9.6-2 [257 kB]
Get:2
http://autoinstall.plesk.com/debian/PSA_12.0.18/ wheezy/all plesk-mail-pc-driver amd64 12.0.18-debian7.0.build1200140610.11 [2576 kB]
Use of uninitialized value in concatenation (.) or string at /usr/share/perl5/Debconf/DbDriver/File.pm line 44, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value in -e at /usr/share/perl5/Debconf/DbDriver/File.pm line 46, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value in pattern match (m//) at /usr/share/perl5/Debconf/DbDriver/File.pm line 47, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value $directory in -d at /usr/share/perl5/Debconf/DbDriver/File.pm line 48, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value $directory in concatenation (.) or string at /usr/share/perl5/Debconf/DbDriver/File.pm line 49, <DEBCONF_CONFIG> chunk 3.
debconf: DbDriver "config": mkdir :No such file or directory
Fetched 2833 kB in 0s (25.2 MB/s)
(Reading database ... 133954 files and directories currently installed.)
Unpacking postfix (from .../postfix_2.9.6-2_amd64.deb) ...
Use of uninitialized value in concatenation (.) or string at /usr/share/perl5/Debconf/DbDriver/File.pm line 44, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value in -e at /usr/share/perl5/Debconf/DbDriver/File.pm line 46, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value in pattern match (m//) at /usr/share/perl5/Debconf/DbDriver/File.pm line 47, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value $directory in -d at /usr/share/perl5/Debconf/DbDriver/File.pm line 48, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value $directory in concatenation (.) or string at /usr/share/perl5/Debconf/DbDriver/File.pm line 49, <DEBCONF_CONFIG> chunk 3.
debconf: DbDriver "config": mkdir :No such file or directory
dpkg: error processing /var/cache/apt/archives/postfix_2.9.6-2_amd64.deb (--unpack):
subprocess new pre-installation script returned error exit status 1
Selecting previously unselected package postfix-pcre.
Unpacking postfix-pcre (from .../postfix-pcre_2.9.6-2_amd64.deb) ...
Errors were encountered while processing:
/var/cache/apt/archives/postfix_2.9.6-2_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
Error: An error occurred on attempt to install packages.
Attention! Your software might be inoperable.
Please, contact product technical support.