Current Perl documentation can be found at perldoc.perl.org.
Here is our local, out-dated (pre-5.6) version:
For a quick-and-dirty solution, try this solution derived from page 222 of the 2nd edition of ``Programming Perl'':
$/ = ''; $header = <MSG>; $header =~ s/\n\s+/ /g; # merge continuation lines %head = ( UNIX_FROM_LINE, split /^([-\w]+):\s*/m, $header );
That solution doesn't do well if, for example, you're trying to maintain all the Received lines. A more complete approach is to use the Mail::Header module from CPAN (part of the MailTools package).