[root@www mail]# cat reader.pl
#!/usr/bin/perl
use BerkeleyDB;
tie %hash, 'BerkeleyDB::Hash', -Filename => $ARGV[0]
    or die "can't read file '$ARGV[0]': $!";
print map { "  $_ => $hash{$_}\n" } sort keys %hash;

[root@www mail]# ./reader.pl virtusertable.db
  @blech.com.au => blech.com.au
  [snip]