use Email::Address;

my @addresses = map { Email::Address->parse($_) } <DATA>;

print is_equivalent(@addresses) ? '' : 'not ' , "equivalent\n";

sub is_equivalent {
    my ($a, $b) = @_;

    return lc $a->address eq lc $b->address;
}

__DATA__
"John Doe" <jdoe@bla.com> (Johnnie "Two Toes")
jDOE@BLA.COM

##</code><code>##

use Email::Address;

my @addresses = map { Email::Address->parse( $_ ) } <DATA>;

for my $address (@addresses) {
    printf("%8s: %s\n", $_, ( $address->$_ or '' ) ) for ( qw( original address user host name phrase comment format ) );
    print "-------\n";
}

__DATA__
abc@foo.com
bla@gmail
"Eve Rybody" <everybody@example.com>
foo@asdf.com%bar.com
"Alan B. Combs" <abc@foo.com> (I can't think of anything complex)