my $string = 'to=<adam.clark@ngv.vic.gov.au>, relay=monet1.ngv.vic.gov.au[10.10.10.20]:25, delay=0.54, delays=0.06/0.02/0/0.46, dsn=2.0.0, status=sent ';

$LogLineHash = qr {
        ^
        ([^=]*)=<?(.*?)>?,?\s+)
        (.*?)
        $
}xi;

while ( $string ){
        print "String: $string\n";
        ( $junk , $key , $value, $string  )
                = split( /$LogLineHash/ , $string );

        print "Key: $key\nValue: $value\nLeft Over: $string\n\n";
        $Hash{$key}=$value;
}

while ( my ($key, $value) = each(%Hash) ) {
        print "$key => $value\n";
    }

##</code><code>##

String: to=<adam.clark@ngv.vic.gov.au>, relay=monet1.ngv.vic.gov.au[10.10.10.20]:25, delay=0.54, delays=0.06/0.02/0/0.46, dsn=2.0.0, status=sent
Key: to
Value: adam.clark@ngv.vic.gov.au
Left Over: relay=monet1.ngv.vic.gov.au[10.10.10.20]:25, delay=0.54, delays=0.06/0.02/0/0.46, dsn=2.0.0, status=sent

String: relay=monet1.ngv.vic.gov.au[10.10.10.20]:25, delay=0.54, delays=0.06/0.02/0/0.46, dsn=2.0.0, status=sent
Key: relay
Value: monet1.ngv.vic.gov.au[10.10.10.20]:25
Left Over: delay=0.54, delays=0.06/0.02/0/0.46, dsn=2.0.0, status=sent

String: delay=0.54, delays=0.06/0.02/0/0.46, dsn=2.0.0, status=sent
Key: delay
Value: 0.54
Left Over: delays=0.06/0.02/0/0.46, dsn=2.0.0, status=sent

String: delays=0.06/0.02/0/0.46, dsn=2.0.0, status=sent
Key: delays
Value: 0.06/0.02/0/0.46
Left Over: dsn=2.0.0, status=sent

String: dsn=2.0.0, status=sent
Key: dsn
Value: 2.0.0
Left Over: status=sent

String: status=sent
Key: status
Value: sent
Left Over:

relay => monet1.ngv.vic.gov.au[10.10.10.20]:25
to => adam.clark@ngv.vic.gov.au
dsn => 2.0.0
status => sent
delay => 0.54
delays => 0.06/0.02/0/0.46

##</code><code>##

^(?:([^=]*)=<?(.*?)>?,?\s+)+$

##</code><code>##

my @bits = split( /^(?:([^=]*)=<?(.*?)>?,?\s+)+$/ , $string );
foreach ( @bits ){
    print "$_\n";
}

##</code><code>##

status
sent