open (MYFILE, 'data.txt');
while (<MYFILE>) {
    chomp;
    my @words = split(' ');
    foreach my $word (@words) {
        if($word =~ /.+@.+..{2,6}/) {
            print "$_n";
        }
    }
}

use Email::Valid;
open (MYFILE, 'data.txt');
while (<MYFILE>) {
    chomp;
    my @words = split(' ');
    foreach my $word (@words) {
        if(Email::Valid->address($word)) {
            print "$wordn";
        }
    }
}

print "$_n";

print "$wordn";

open (MYFILE, 'data.txt');
    while (<MYFILE>) {
        chomp;
        my @words = split(' ');
        foreach my $word (@words) {
            if($word =~ /^[^@]+@+[^.]+.+[^.]{2,6}$/) {
                print "$wordn";
            }
        }
    }

me@me.com mine@mine.co.uk myself@email.net
me@me.com mine@mine.in myself@email.ru
me@me.com mine@mine.co.uk myself@email.america

Output
------
me@me.com
myself@email.net
me@me.com
mine@mine.in
myself@email.ru
me@me.com

/bw+(.?[*+-=^$#!~?w])*@w+(.?[*+-=^$#!~?w])*w+b/