SMTP Mail Queueing improvements

Sources/ManageMail.php

@@ -249,6 +249,8 @@ function list_getMailQueue($start, $items_per_page, $sort)
  // Private PM/email subjects and similar shouldn't be shown in the mailbox area.
  if (!empty($row['private']))
  $row['subject'] = $txt['personal_message'];
+ else
+ $row['subject'] = mb_decode_mimeheader($row['subject']);
 
  $mails[] = $row;
  }

Sources/ScheduledTasks.php

@@ -712,7 +712,7 @@ function ReduceMailQueue($number = false, $override_limit = false, $force_send =
 
  // Now we know how many we're sending, let's send them.
  $request = $smcFunc['db_query']('', '
- SELECT id_mail, recipient, body, subject, headers, send_html, time_sent, private
+ SELECT id_mail, recipient, body, subject, headers, send_html, time_sent, private, priority
  FROM {db_prefix}mail_queue
  ORDER BY priority ASC, id_mail ASC
  LIMIT {int:limit}',
@@ -734,6 +734,7 @@ function ReduceMailQueue($number = false, $override_limit = false, $force_send =
  'send_html' => $row['send_html'],
  'time_sent' => $row['time_sent'],
  'private' => $row['private'],
+ 'priority' => $row['priority'],
  );
  }
  $smcFunc['db_free_result']($request);
@@ -772,8 +773,18 @@ function ReduceMailQueue($number = false, $override_limit = false, $force_send =
 
  // Send each email, yea!
  $failed_emails = array();
+ $max_priority = 127;
+ $smtp_expire = 259200;
+ $priority_offset = 4;
  foreach ($emails as $email)
  {
+ // This seems odd, but check the priority if we should try again so soon. Do this so we don't DOS some poor mail server.
+ if ($email['priority'] > $priority_offset && (time() - $email['time_sent']) % $priority_offset != rand(0, $priority_offset))
+ {
+ $failed_emails[] = array($email['to'], $email['body'], $email['subject'], $email['headers'], $email['send_html'], $email['time_sent'], $email['private'], $email['priority']);
+ continue;
+ }
+
  if (empty($modSettings['mail_type']) || $modSettings['smtp_host'] == '')
  {
  $email['subject'] = strtr($email['subject'], array("\r" => '', "\n" => ''));
@@ -794,11 +805,21 @@ function ReduceMailQueue($number = false, $override_limit = false, $force_send =
  else
  $result = smtp_mail(array($email['to']), $email['subject'], $email['body'], $email['headers']);
 
+ // Old emails should expire
+ if (!$result && $email['priority'] >= $max_priority)
+ $result = true;
+
  // Hopefully it sent?
  if (!$result)
- $failed_emails[] = array($email['to'], $email['body'], $email['subject'], $email['headers'], $email['send_html'], $email['time_sent'], $email['private']);
+ {
+ // Determine the "priority" as a way to keep track of SMTP failures.
+ $email['priority'] = max($priority_offset, $email['priority'], min(ceil((time() - $email['time_sent']) / $smtp_expire * ($max_priority - $priority_offset)) + $priority_offset, $max_priority));
+
+ $failed_emails[] = array($email['to'], $email['body'], $email['subject'], $email['headers'], $email['send_html'], $email['time_sent'], $email['private'], $email['priority']);
+ }
  }
 
+
  // Any emails that didn't send?
  if (!empty($failed_emails))
  {
@@ -826,7 +847,7 @@ function ReduceMailQueue($number = false, $override_limit = false, $force_send =
  // Add our email back to the queue, manually.
  $smcFunc['db_insert']('insert',
  '{db_prefix}mail_queue',
- array('recipient' => 'string', 'body' => 'string', 'subject' => 'string', 'headers' => 'string', 'send_html' => 'string', 'time_sent' => 'string', 'private' => 'int'),
+ array('recipient' => 'string', 'body' => 'string', 'subject' => 'string', 'headers' => 'string', 'send_html' => 'string', 'time_sent' => 'string', 'private' => 'int', 'priority' => 'int'),
  $failed_emails,
  array('id_mail')
  );

Sources/Subs-Post.php

@@ -1592,9 +1592,17 @@ function server_parse($message, $socket, $code, &$response = null)
  if ($code === null)
  return substr($server_response, 0, 3);
 
- if (substr($server_response, 0, 3) != $code)
+ $response_code = (int) substr($server_response, 0, 3);
+ if ($response_code != $code)
  {
- log_error($txt['smtp_error'] . $server_response);
+ // Ignoreable errors that we can't fix should not be logged.
+ /*
+ * 550 - cPanel rejected sending due to DNS issues
+ * 450 - DNS Routing issues
+ */
+ if ($response_code < 500 && $response_code != 450))
+ log_error($txt['smtp_error'] . $server_response);
+
  return false;
  }