Hi,
First of all, I'm fairly sure you don't need to run a mailserver at all, you just need a box with internet access to an ISP that accepts mails from you.
You can use modules such as Net::SMTP to send the mail.
here's some code which I've dug out of another script. It's untested in its current form

#!/usr/bin/perl -w

use strict;
use Net::SMTP;

my $mailserver      = "mailserver.yourisp.com";

my $mailfrom = "From: \"Big Company\" <big_company\@domain.com>\n";
my $mailto   = "To: \"Joe Blogs\" <joe_bloggs\@clients.com>\n";

my $subject = "Blah, blah, blah";

foreach $infile (@ARGV) {

        if(!open MESSAGE, "<$infile") {
                print STDERR "Couldn't open $infile: $!\n";
                next;
        }
        my $message;

        my $smtp = Net::SMTP->new($mailserver);

        my $mailfrom = $1 if($displaymailfrom =~ /^[^<]*<([^>]+)>/);
        my $mailto   = $1 if($displaymailto   =~ /^[^<]*<([^>]+)>/);

        $smtp->mail($mailfrom);
        $smtp->to($mailto);

        $smtp->data();
        $smtp->datasend($subject);

        $smtp->datasend($displaymailfrom);
        $smtp->datasend($displaymailto);

        while(<MESSAGE>) {
                $smtp->datasend($_);
        }
        $smtp->dataend();
        $smtp->quit;


        close MESSAGE;
}
[download]

Hope that helps