Hi Oukz,
Really, aitap's wisdom for me is the way to go, however, if I may suggest using here-document like so:

use warnings;
use strict;

my $first_name = "James";
my $company    = "SoftLayer";

my $letter = << "COMPANY_LETTER";
Hello $first_name. 

I'm writing on behalf of $company ....

COMPANY_LETTER

my $outfile = "new.txt";

open my $fh, '>', $outfile or die "Can't open file: $!";

print $fh $letter;

close $fh or die "can't close file: $!";
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