#!/usr/bin/perl
use strict;
use warnings qw( all );
use feature qw( say );

my @chars = ('0'..'9');
my $len = 4;
my $x = shift // 1;

for (1..$x) {
    my $num = '';
    for (1..$len) {
        $num .= $chars[int rand @chars];
    }

    say 'sme_' . $num . '@dispostable.com;';
}