Use the \w character class and you should get the desired results e.g

my $str   = 'blah @letters12345andsoon. blah';
my($data) = $str =~ /@(\w+)\./;

print "got - $data\n";

__output__

got - letters12345andsoon
[download]

See. perlre for more info.
HTH

_________
broquaint