It's trivial using Time::Piece:

#!/usr/bin/env perl 
use strict;
use warnings;
use Time::Piece;

my $fmt = '%a, %e, %b %Y %T %z';
my $sent = Time::Piece->strptime ('Wed, 01 Nov 2017 09:07:05 +1100', $
+fmt);
my $recd = Time::Piece->strptime ('Tue, 31 Oct 2017 15:07:32 -0700', $
+fmt);
my $duration = $recd - $sent;
print "Took $duration seconds\n";
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