diff --git a/lib/classes/phpmailer/class.PHPMailer.php b/lib/classes/phpmailer/class.PHPMailer.php
index e4dd00bf..89d97316 100644
--- a/lib/classes/phpmailer/class.PHPMailer.php
+++ b/lib/classes/phpmailer/class.PHPMailer.php
@@ -31,7 +31,7 @@ class PHPMailer
      * The PHPMailer Version number.
      * @var string
      */
-    public $Version = '5.2.14';
+    public $Version = '5.2.15';
 
     /**
      * Email priority.
@@ -352,6 +352,7 @@ class PHPMailer
     /**
      * Whether to split multiple to addresses into multiple messages
      * or send them all in one message.
+     * Only supported in `mail` and `sendmail` transports, not in SMTP.
      * @var boolean
      */
     public $SingleTo = false;
@@ -446,6 +447,15 @@ class PHPMailer
      */
     public $XMailer = '';
 
+    /**
+     * Which validator to use by default when validating email addresses.
+     * May be a callable to inject your own validator, but there are several built-in validators.
+     * @see PHPMailer::validateAddress()
+     * @var string|callable
+     * @static
+     */
+    public static $validator = 'auto';
+
     /**
      * An instance of the SMTP sender class.
      * @var SMTP
@@ -634,9 +644,11 @@ class PHPMailer
      * Constructor.
      * @param boolean $exceptions Should we throw external exceptions?
      */
-    public function __construct($exceptions = false)
+    public function __construct($exceptions = null)
     {
-        $this->exceptions = (boolean)$exceptions;
+        if ($exceptions !== null) {
+            $this->exceptions = (boolean)$exceptions;
+        }
     }
 
     /**
@@ -645,9 +657,7 @@ class PHPMailer
     public function __destruct()
     {
         //Close any open SMTP connection nicely
-        if ($this->Mailer == 'smtp') {
-            $this->smtpClose();
-        }
+        $this->smtpClose();
     }
 
     /**
@@ -713,7 +723,7 @@ class PHPMailer
             case 'echo':
             default:
                 //Normalize line breaks
-                $str = preg_replace('/(\r\n|\r|\n)/ms', "\n", $str);
+                $str = preg_replace('/\r\n?/ms', "\n", $str);
                 echo gmdate('Y-m-d H:i:s') . "\t" . str_replace(
                     "\n",
                     "\n                   \t                  ",
@@ -850,7 +860,7 @@ class PHPMailer
         $name = trim(preg_replace('/[\r\n]+/', '', $name)); //Strip breaks and trim
         if (($pos = strrpos($address, '@')) === false) {
             // At-sign is misssing.
-            $error_message = $this->lang('invalid_address') . $address;
+            $error_message = $this->lang('invalid_address') . " (addAnAddress $kind): $address";
             $this->setError($error_message);
             $this->edebug($error_message);
             if ($this->exceptions) {
@@ -900,7 +910,7 @@ class PHPMailer
             return false;
         }
         if (!$this->validateAddress($address)) {
-            $error_message = $this->lang('invalid_address') . $address;
+            $error_message = $this->lang('invalid_address') . " (addAnAddress $kind): $address";
             $this->setError($error_message);
             $this->edebug($error_message);
             if ($this->exceptions) {
@@ -994,7 +1004,7 @@ class PHPMailer
         if (($pos = strrpos($address, '@')) === false or
             (!$this->has8bitChars(substr($address, ++$pos)) or !$this->idnSupported()) and
             !$this->validateAddress($address)) {
-            $error_message = $this->lang('invalid_address') . $address;
+            $error_message = $this->lang('invalid_address') . " (setFrom) $address";
             $this->setError($error_message);
             $this->edebug($error_message);
             if ($this->exceptions) {
@@ -1027,19 +1037,30 @@ class PHPMailer
     /**
      * Check that a string looks like an email address.
      * @param string $address The email address to check
-     * @param string $patternselect A selector for the validation pattern to use :
+     * @param string|callable $patternselect A selector for the validation pattern to use :
      * * `auto` Pick best pattern automatically;
      * * `pcre8` Use the squiloople.com pattern, requires PCRE > 8.0, PHP >= 5.3.2, 5.2.14;
      * * `pcre` Use old PCRE implementation;
      * * `php` Use PHP built-in FILTER_VALIDATE_EMAIL;
      * * `html5` Use the pattern given by the HTML5 spec for 'email' type form input elements.
      * * `noregex` Don't use a regex: super fast, really dumb.
+     * Alternatively you may pass in a callable to inject your own validator, for example:
+     * PHPMailer::validateAddress('user@example.com', function($address) {
+     *     return (strpos($address, '@') !== false);
+     * });
+     * You can also set the PHPMailer::$validator static to a callable, allowing built-in methods to use your validator.
      * @return boolean
      * @static
      * @access public
      */
-    public static function validateAddress($address, $patternselect = 'auto')
+    public static function validateAddress($address, $patternselect = null)
     {
+        if (is_null($patternselect)) {
+            $patternselect = self::$validator;
+        }
+        if (is_callable($patternselect)) {
+            return call_user_func($patternselect, $address);
+        }
         //Reject line breaks in addresses; it's valid RFC5322, but not RFC5321
         if (strpos($address, "\n") !== false or strpos($address, "\r") !== false) {
             return false;
@@ -1216,7 +1237,7 @@ class PHPMailer
                 }
                 $this->$address_kind = $this->punyencodeAddress($this->$address_kind);
                 if (!$this->validateAddress($this->$address_kind)) {
-                    $error_message = $this->lang('invalid_address') . $this->$address_kind;
+                    $error_message = $this->lang('invalid_address') . ' (punyEncode) ' . $this->$address_kind;
                     $this->setError($error_message);
                     $this->edebug($error_message);
                     if ($this->exceptions) {
@@ -1227,7 +1248,7 @@ class PHPMailer
             }
 
             // Set whether the message is multipart/alternative
-            if (!empty($this->AltBody)) {
+            if ($this->alternativeExists()) {
                 $this->ContentType = 'multipart/alternative';
             }
 
@@ -1634,7 +1655,7 @@ class PHPMailer
      */
     public function smtpClose()
     {
-        if ($this->smtp !== null) {
+        if (is_a($this->smtp, 'SMTP')) {
             if ($this->smtp->connected()) {
                 $this->smtp->quit();
                 $this->smtp->close();
@@ -1972,7 +1993,7 @@ class PHPMailer
             $result .= $this->headerLine('Subject', $this->encodeHeader($this->secureHeader($this->Subject)));
         }
 
-        if ($this->MessageID != '') {
+        if ('' != $this->MessageID and preg_match('/^<.*@.*>$/', $this->MessageID)) {
             $this->lastMessageID = $this->MessageID;
         } else {
             $this->lastMessageID = sprintf('<%s@%s>', $this->uniqueid, $this->serverHostname());
@@ -2074,7 +2095,7 @@ class PHPMailer
      */
     public function getSentMIMEMessage()
     {
-        return $this->MIMEHeader . $this->mailHeader . self::CRLF . $this->MIMEBody;
+        return rtrim($this->MIMEHeader . $this->mailHeader, "\n\r") . self::CRLF . self::CRLF . $this->MIMEBody;
     }
 
     /**
@@ -2120,8 +2141,9 @@ class PHPMailer
             $altBodyEncoding = '7bit';
             $altBodyCharSet = 'us-ascii';
         }
-        //If lines are too long, change to quoted-printable transfer encoding
-        if (self::hasLineLongerThanMax($this->AltBody)) {
+        //If lines are too long, and we're not already using an encoding that will shorten them,
+        //change to quoted-printable transfer encoding
+        if ('base64' != $altBodyEncoding and self::hasLineLongerThanMax($this->AltBody)) {
             $altBodyEncoding = 'quoted-printable';
         }
         //Use this as a preamble in all multipart message types
@@ -3296,7 +3318,7 @@ class PHPMailer
                             $message
                         );
                     }
-                } elseif (substr($url, 0, 4) !== 'cid:' && !preg_match('#^[A-z]+://#', $url)) {
+                } elseif (substr($url, 0, 4) !== 'cid:' && !preg_match('#^[a-z][a-z0-9+.-]*://#i', $url)) {
                     // Do not change urls for absolute images (thanks to corvuscorax)
                     // Do not change urls that are already inline images
                     $filename = basename($url);
@@ -3332,7 +3354,7 @@ class PHPMailer
         // Convert all message body line breaks to CRLF, makes quoted-printable encoding work much better
         $this->Body = $this->normalizeBreaks($message);
         $this->AltBody = $this->normalizeBreaks($this->html2text($message, $advanced));
-        if (empty($this->AltBody)) {
+        if (!$this->alternativeExists()) {
             $this->AltBody = 'To view this email message, open it in a program that understands HTML!' .
                 self::CRLF . self::CRLF;
         }
@@ -3657,11 +3679,13 @@ class PHPMailer
         if ($this->DKIM_passphrase != '') {
             $privKey = openssl_pkey_get_private($privKeyStr, $this->DKIM_passphrase);
         } else {
-            $privKey = $privKeyStr;
+            $privKey = openssl_pkey_get_private($privKeyStr);
         }
-        if (openssl_sign($signHeader, $signature, $privKey)) {
+        if (openssl_sign($signHeader, $signature, $privKey, 'sha256WithRSAEncryption')) { //sha1WithRSAEncryption
+            openssl_pkey_free($privKey);
             return base64_encode($signature);
         }
+        openssl_pkey_free($privKey);
         return '';
     }
 
@@ -3678,7 +3702,7 @@ class PHPMailer
         foreach ($lines as $key => $line) {
             list($heading, $value) = explode(':', $line, 2);
             $heading = strtolower($heading);
-            $value = preg_replace('/\s+/', ' ', $value); // Compress useless spaces
+            $value = preg_replace('/\s{2,}/', ' ', $value); // Compress useless spaces
             $lines[$key] = $heading . ':' . trim($value); // Don't forget to remove WSP around the value
         }
         $signHeader = implode("\r\n", $lines);
@@ -3716,7 +3740,7 @@ class PHPMailer
      */
     public function DKIM_Add($headers_line, $subject, $body)
     {
-        $DKIMsignatureType = 'rsa-sha1'; // Signature & hash algorithms
+        $DKIMsignatureType = 'rsa-sha256'; // Signature & hash algorithms
         $DKIMcanonicalization = 'relaxed/simple'; // Canonicalization of header/body
         $DKIMquery = 'dns/txt'; // Query method
         $DKIMtime = time(); // Signature Timestamp = seconds since 00:00:00 - Jan 1, 1970 (UTC time zone)
@@ -3724,6 +3748,7 @@ class PHPMailer
         $headers = explode($this->LE, $headers_line);
         $from_header = '';
         $to_header = '';
+        $date_header = '';
         $current = '';
         foreach ($headers as $header) {
             if (strpos($header, 'From:') === 0) {
@@ -3732,6 +3757,9 @@ class PHPMailer
             } elseif (strpos($header, 'To:') === 0) {
                 $to_header = $header;
                 $current = 'to_header';
+            } elseif (strpos($header, 'Date:') === 0) {
+                $date_header = $header;
+                $current = 'date_header';
             } else {
                 if (!empty($$current) && strpos($header, ' =?') === 0) {
                     $$current .= $header;
@@ -3742,6 +3770,7 @@ class PHPMailer
         }
         $from = str_replace('|', '=7C', $this->DKIM_QP($from_header));
         $to = str_replace('|', '=7C', $this->DKIM_QP($to_header));
+        $date = str_replace('|', '=7C', $this->DKIM_QP($date_header));
         $subject = str_replace(
             '|',
             '=7C',
@@ -3749,7 +3778,7 @@ class PHPMailer
         ); // Copied header fields (dkim-quoted-printable)
         $body = $this->DKIM_BodyC($body);
         $DKIMlen = strlen($body); // Length of body
-        $DKIMb64 = base64_encode(pack('H*', sha1($body))); // Base64 of packed binary SHA-1 hash of body
+        $DKIMb64 = base64_encode(pack('H*', hash('sha256', $body))); // Base64 of packed binary SHA-256 hash of body
         if ('' == $this->DKIM_identity) {
             $ident = '';
         } else {
@@ -3762,16 +3791,18 @@ class PHPMailer
             $this->DKIM_selector .
             ";\r\n" .
             "\tt=" . $DKIMtime . '; c=' . $DKIMcanonicalization . ";\r\n" .
-            "\th=From:To:Subject;\r\n" .
+            "\th=From:To:Date:Subject;\r\n" .
             "\td=" . $this->DKIM_domain . ';' . $ident . "\r\n" .
             "\tz=$from\r\n" .
             "\t|$to\r\n" .
+            "\t|$date\r\n" .
             "\t|$subject;\r\n" .
             "\tbh=" . $DKIMb64 . ";\r\n" .
             "\tb=";
         $toSign = $this->DKIM_HeaderC(
             $from_header . "\r\n" .
             $to_header . "\r\n" .
+            $date_header . "\r\n" .
             $subject_header . "\r\n" .
             $dkimhdrs
         );
diff --git a/lib/classes/phpmailer/class.SMTP.php b/lib/classes/phpmailer/class.SMTP.php
index 2e32e2fc..039f8beb 100644
--- a/lib/classes/phpmailer/class.SMTP.php
+++ b/lib/classes/phpmailer/class.SMTP.php
@@ -30,7 +30,7 @@ class SMTP
      * The PHPMailer SMTP version number.
      * @var string
      */
-    const VERSION = '5.2.14';
+    const VERSION = '5.2.15';
 
     /**
      * SMTP line break constant.
@@ -81,7 +81,7 @@ class SMTP
      * @deprecated Use the `VERSION` constant instead
      * @see SMTP::VERSION
      */
-    public $Version = '5.2.14';
+    public $Version = '5.2.15';
 
     /**
      * SMTP server port number.
@@ -336,11 +336,22 @@ class SMTP
         if (!$this->sendCommand('STARTTLS', 'STARTTLS', 220)) {
             return false;
         }
+
+        //Allow the best TLS version(s) we can
+        $crypto_method = STREAM_CRYPTO_METHOD_TLS_CLIENT;
+
+        //PHP 5.6.7 dropped inclusion of TLS 1.1 and 1.2 in STREAM_CRYPTO_METHOD_TLS_CLIENT
+        //so add them back in manually if we can
+        if (defined('STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT')) {
+            $crypto_method |= STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT;
+            $crypto_method |= STREAM_CRYPTO_METHOD_TLSv1_1_CLIENT;
+        }
+
         // Begin encrypted connection
         if (!stream_socket_enable_crypto(
             $this->smtp_conn,
             true,
-            STREAM_CRYPTO_METHOD_TLS_CLIENT
+            $crypto_method
         )) {
             return false;
         }
@@ -736,7 +747,7 @@ class SMTP
     protected function parseHelloFields($type)
     {
         $this->server_caps = array();
-        $lines = explode("\n", $this->last_reply);
+        $lines = explode("\n", $this->helo_rply);
 
         foreach ($lines as $n => $s) {
             //First 4 chars contain response code followed by - or space