When you're talking about "deduping" or "seeing if I've already seen one of these", you're talking about hashes.

Take the following sample code:

my %seen;
foreach my $addr ( @bigaddrlist ) {
    ++$seen{ $addr };
} # foreach

my @deduped = keys %seen;
[download]

If preserving order is important, do something like so:

my %seen;
my @deduped;
foreach my $addr ( @bigaddrlist ) {
    push( @deduped, $addr ) unless $seen{$addr}++;
}
[download]

xoxo,
Andy

%_=split/;/,".;;n;u;e;ot;t;her;c; ".   #   Andy Lester
'Perl ;@; a;a;j;m;er;y;t;p;n;d;s;o;'.  #   http://petdance.com
"hack";print map delete$_{$_},split//,q<   andy@petdance.com   >