#!/usr/bin/env perl 
use strict;
use warnings;
use Data::Dumper;

my %parts;
my $key;

while (my $line = <DATA>) {
    if ($line =~ /^([A-Z]+)$/) {
        $key = $1;
        if ($key =~ /^END/) { undef $key; }
        next;
    }
    next unless defined $key;
    $parts{$key} //= '';
    $parts{$key} .= $line;
}

print Dumper (\%parts);

__DATA__
TO
rahul@example.com,you@everyone.com
ENDTO

SUBJECT
Weekly status snapshot for WW-5
ENDSUBJECT
BODY
Hi All,
Weekly progress snapshot for this week will be taken on Thursday, 30 Jan at the end of the day. ( Please update your status before the snapshot)
Use work week number as 5 for this week's updates .
Note : If you want any additional data to be picked up ( or dropped ) from your sheets, do work with me so that status collation script can be updated to do this .
Thanks ,
-Ram
ENDBODY