I think that $entry may not be getting initialized properly. I tested your regex with the \@ and it appears to work fine. eg: 
$entry = 'a.address@host.com';
if ($entry !~ /^([a-zA-Z0-9\@_.]*)$/) {
    print "Doh!\n";
    exit;
}
print "Found it\n";

[download]
prints "Found it!"

In reply to Re: @ in regex, or not? by the_slycer
in thread @ in regex, or not? by JPaul

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