Linux Mail Server Setup and Howto Guide

i've just installed a centOS 5.6 and follow the step through.

Mailscanner instalation completed succesfully, but when i try to start the service the following error occured :

Can't locate Sys/SigAction.pm in @INC (@INC contains: /usr/lib/MailScanner /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.8 /usr/lib/perl5/vendor_perl /usr/lib/perl5/5.8.8/i386-linux-thread-multi /usr/lib/perl5/5.8.8 .) at /usr/lib/MailScanner/MailScanner/ConfigSQL.pm line 38.
BEGIN failed–compilation aborted at /usr/lib/MailScanner/MailScanner/ConfigSQL.pm line 38.
Compilation failed in require at /usr/lib/MailScanner/MailScanner/Config.pm line 47.
Compilation failed in require.
BEGIN failed–compilation aborted.
Can't locate Sys/SigAction.pm in @INC (@INC contains: /usr/lib/MailScanner /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.8 /usr/lib/perl5/vendor_perl /usr/lib/perl5/5.8.8/i386-linux-thread-multi /usr/lib/perl5/5.8.8 .) at /usr/lib/MailScanner/MailScanner/ConfigSQL.pm line 38.
BEGIN failed–compilation aborted at /usr/lib/MailScanner/MailScanner/ConfigSQL.pm line 38.
Compilation failed in require at /usr/lib/MailScanner/MailScanner/Config.pm line 47.
Compilation failed in require.
BEGIN failed–compilation aborted.
Can't locate Sys/SigAction.pm in @INC (@INC contains: /usr/lib/MailScanner /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.8 /usr/lib/perl5/vendor_perl /usr/lib/perl5/5.8.8/i386-linux-thread-multi /usr/lib/perl5/5.8.8 .) at /usr/lib/MailScanner/MailScanner/ConfigSQL.pm line 38.
BEGIN failed–compilation aborted at /usr/lib/MailScanner/MailScanner/ConfigSQL.pm line 38.
Compilation failed in require at /usr/lib/MailScanner/MailScanner/Config.pm line 47.
Compilation failed in require.
BEGIN failed–compilation aborted.
Can't locate Sys/SigAction.pm in @INC (@INC contains: /usr/lib/MailScanner /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.8 /usr/lib/perl5/vendor_perl /usr/lib/perl5/5.8.8/i386-linux-thread-multi /usr/lib/perl5/5.8.8 .) at /usr/lib/MailScanner/MailScanner/ConfigSQL.pm line 38.
BEGIN failed–compilation aborted at /usr/lib/MailScanner/MailScanner/ConfigSQL.pm line 38.
Compilation failed in require at /usr/lib/MailScanner/MailScanner/Config.pm line 47.
Compilation failed in require.
BEGIN failed–compilation aborted.
Can't locate Sys/SigAction.pm in @INC (@INC contains: /usr/lib/MailScanner /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.8 /usr/lib/perl5/vendor_perl /usr/lib/perl5/5.8.8/i386-linux-thread-multi /usr/lib/perl5/5.8.8 .) at /usr/lib/MailScanner/MailScanner/ConfigSQL.pm line 38.
BEGIN failed–compilation aborted at /usr/lib/MailScanner/MailScanner/ConfigSQL.pm line 38.
Compilation failed in require at /usr/lib/MailScanner/MailScanner/Config.pm line 47.
Compilation failed in require.
BEGIN failed–compilation aborted.
/etc/init.d/MailScanner: line 84: [: =: unary operator expected
Checking MailScanner daemons:
         MailScanner:       [FAILED]

/etc/init.d/MailScanner: line 335: [: =: unary operator expected
/etc/init.d/MailScanner: line 349: [: =: unary operator expected

i'm new at this OS and can't find the cause of it, any help would greatly apreciated

thanks in advance.