You get only "forward", because you ask regexp to filter it for you ;)

if (/^Subject:(\s+)(\S+).*$/
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This means, show me the whitespaces between "Subject:" and the next non-whitespace as $1. Then, show me every non-whitespace character to the next whitespace, as $2.

This will solve it:

if (/^Subject:(\s+)(.*)$/) {
   $subject = $2;
}
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