small fix

Author: francescobianco

src/BodyStructure.php

@@ -313,7 +313,7 @@ protected static function processSubPartAsMessage($item)
                 continue;
             }
 
-            if (!is_array($itemPart[2])) {
+            if (empty($itemPart[2]) || !is_array($itemPart[2])) {
                 continue;
             }
 

src/Connection.php

@@ -52,7 +52,7 @@ public function openMailbox($mailbox)
         $mailboxParts = Functions::parseMailboxString($mailbox);
 
         $this->host = Functions::getHostFromMailbox($mailboxParts);
-        $this->port = $mailboxParts['port'];
+        $this->port = @$mailboxParts['port'];
         $this->sslMode = Functions::getSslModeFromMailbox($mailboxParts);
         $this->currentMailbox = $mailboxParts['mailbox'];
     }