This did it...
$horvitzaddresses = explode(', ',$_POST['horvitzaddresses']);
$kcjaddresses = explode(', ',$_POST['kcjaddresses']);
$miraddresses = explode(', ',$_POST['miraddresses']);
$pdnaddresses = explode(', ',$_POST['pdnaddresses']);
$rnaddresses = explode(', ',$_POST['rnaddresses']);
$tdtaddresses = explode(', ',$_POST['tdtaddresses']);
$svraddresses = explode(', ',$_POST['svraddresses']);
$newaddresses = array('main' => $mainaddresses,
'horvitznewspapers' => $horvitzaddresses,
'kingcountyjournal' => $kcjaddresses,
'mireporter' => $miraddresses,
'peninsuladailynews' => $pdnaddresses,
'reporternewspapers' => $rnaddresses,
'thedailytimes' => $tdtaddresses,
'valleyrecord' => $svraddresses);
foreach ($newaddresses as $locations => $domainlist){
foreach ($domainlist as $address => $addresslist){
$info['maildrop'][$address] = $addresslist;
echo "<br><br>$address : $addresslist<br><br>";
}
}