Update phpmailer/phpmailer requirement from 6.10.0 to 6.11.1 in /lib (#8048)

* Update phpmailer/phpmailer requirement from 6.10.0 to 6.11.1 in /lib

Updates the requirements on [phpmailer/phpmailer](https://github.com/PHPMailer/PHPMailer) to permit the latest version.
- [Release notes](https://github.com/PHPMailer/PHPMailer/releases)
- [Changelog](https://github.com/PHPMailer/PHPMailer/blob/master/changelog.md)
- [Commits](https://github.com/PHPMailer/PHPMailer/compare/v6.10.0...v6.11.1)

---
updated-dependencies:
- dependency-name: phpmailer/phpmailer
  dependency-version: 6.11.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

* composer update --no-autoloader

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Alexandre Alapetite <alexandre@alapetite.fr>

4 files changed, 285 insertions, 146 deletions

diff --git a/lib/phpmailer/phpmailer/README.md b/lib/phpmailer/phpmailer/README.md
index 862a4e1a4..51c97517f 100644
--- a/lib/phpmailer/phpmailer/README.md
+++ b/lib/phpmailer/phpmailer/README.md
@@ -48,7 +48,7 @@ This software is distributed under the [LGPL 2.1](https://www.gnu.org/licenses/o
 PHPMailer is available on [Packagist](https://packagist.org/packages/phpmailer/phpmailer) (using semantic versioning), and installation via [Composer](https://getcomposer.org) is the recommended way to install PHPMailer. Just add this line to your `composer.json` file:
 
 ```json
-"phpmailer/phpmailer": "^6.10.0"
+"phpmailer/phpmailer": "^6.11.1"
 ```
 
 or run
diff --git a/lib/phpmailer/phpmailer/VERSION b/lib/phpmailer/phpmailer/VERSION
index cf79bf90e..fac714a32 100644
--- a/lib/phpmailer/phpmailer/VERSION
+++ b/lib/phpmailer/phpmailer/VERSION
@@ -1 +1 @@
-6.10.0
+6.11.1
diff --git a/lib/phpmailer/phpmailer/src/PHPMailer.php b/lib/phpmailer/phpmailer/src/PHPMailer.php
index 2444bcf35..0a8711f48 100644
--- a/lib/phpmailer/phpmailer/src/PHPMailer.php
+++ b/lib/phpmailer/phpmailer/src/PHPMailer.php
@@ -561,9 +561,9 @@ class PHPMailer
      *   string  $body          the email body
      *   string  $from          email address of sender
      *   string  $extra         extra information of possible use
-     *                          "smtp_transaction_id' => last smtp transaction id
+     *                          'smtp_transaction_id' => last smtp transaction id
      *
-     * @var string
+     * @var callable|callable-string
      */
     public $action_function = '';
 
@@ -711,7 +711,7 @@ class PHPMailer
      *
      * @var array
      */
-    protected $language = [];
+    protected static $language = [];
 
     /**
      * The number of errors encountered.
@@ -768,7 +768,7 @@ class PHPMailer
      *
      * @var string
      */
-    const VERSION = '6.10.0';
+    const VERSION = '6.11.1';
 
     /**
      * Error severity: message only, continue processing.
@@ -1102,7 +1102,7 @@ class PHPMailer
             //At-sign is missing.
             $error_message = sprintf(
                 '%s (%s): %s',
-                $this->lang('invalid_address'),
+                self::lang('invalid_address'),
                 $kind,
                 $address
             );
@@ -1187,7 +1187,7 @@ class PHPMailer
         if (!in_array($kind, ['to', 'cc', 'bcc', 'Reply-To'])) {
             $error_message = sprintf(
                 '%s: %s',
-                $this->lang('Invalid recipient kind'),
+                self::lang('Invalid recipient kind'),
                 $kind
             );
             $this->setError($error_message);
@@ -1201,7 +1201,7 @@ class PHPMailer
         if (!static::validateAddress($address)) {
             $error_message = sprintf(
                 '%s (%s): %s',
-                $this->lang('invalid_address'),
+                self::lang('invalid_address'),
                 $kind,
                 $address
             );
@@ -1220,12 +1220,16 @@ class PHPMailer
 
                 return true;
             }
-        } elseif (!array_key_exists(strtolower($address), $this->ReplyTo)) {
-            $this->ReplyTo[strtolower($address)] = [$address, $name];
+        } else {
+            foreach ($this->ReplyTo as $replyTo) {
+                if (0 === strcasecmp($replyTo[0], $address)) {
+                    return false;
+                }
+            }
+            $this->ReplyTo[] = [$address, $name];
 
             return true;
         }
-
         return false;
     }
 
@@ -1238,15 +1242,18 @@ class PHPMailer
      * @see https://www.andrew.cmu.edu/user/agreen1/testing/mrbs/web/Mail/RFC822.php A more careful implementation
      *
      * @param string $addrstr The address list string
-     * @param bool   $useimap Whether to use the IMAP extension to parse the list
+     * @param null   $useimap Deprecated argument since 6.11.0.
      * @param string $charset The charset to use when decoding the address list string.
      *
      * @return array
      */
-    public static function parseAddresses($addrstr, $useimap = true, $charset = self::CHARSET_ISO88591)
+    public static function parseAddresses($addrstr, $useimap = null, $charset = self::CHARSET_ISO88591)
     {
+        if ($useimap !== null) {
+            trigger_error(self::lang('deprecated_argument'), E_USER_DEPRECATED);
+        }
         $addresses = [];
-        if ($useimap && function_exists('imap_rfc822_parse_adrlist')) {
+        if (function_exists('imap_rfc822_parse_adrlist')) {
             //Use this built-in parser if it's available
             $list = imap_rfc822_parse_adrlist($addrstr, '');
             // Clear any potential IMAP errors to get rid of notices being thrown at end of script.
@@ -1256,20 +1263,13 @@ class PHPMailer
                     '.SYNTAX-ERROR.' !== $address->host &&
                     static::validateAddress($address->mailbox . '@' . $address->host)
                 ) {
-                    //Decode the name part if it's present and encoded
+                    //Decode the name part if it's present and maybe encoded
                     if (
-                        property_exists($address, 'personal') &&
-                        //Check for a Mbstring constant rather than using extension_loaded, which is sometimes disabled
-                        defined('MB_CASE_UPPER') &&
-                        preg_match('/^=\?.*\?=$/s', $address->personal)
+                        property_exists($address, 'personal')
+                        && is_string($address->personal)
+                        && $address->personal !== ''
                     ) {
-                        $origCharset = mb_internal_encoding();
-                        mb_internal_encoding($charset);
-                        //Undo any RFC2047-encoded spaces-as-underscores
-                        $address->personal = str_replace('_', '=20', $address->personal);
-                        //Decode the name
-                        $address->personal = mb_decode_mimeheader($address->personal);
-                        mb_internal_encoding($origCharset);
+                        $address->personal = static::decodeHeader($address->personal, $charset);
                     }
 
                     $addresses[] = [
@@ -1280,40 +1280,51 @@ class PHPMailer
             }
         } else {
             //Use this simpler parser
-            $list = explode(',', $addrstr);
-            foreach ($list as $address) {
-                $address = trim($address);
-                //Is there a separate name part?
-                if (strpos($address, '<') === false) {
-                    //No separate name, just use the whole thing
-                    if (static::validateAddress($address)) {
-                        $addresses[] = [
-                            'name' => '',
-                            'address' => $address,
-                        ];
-                    }
-                } else {
-                    list($name, $email) = explode('<', $address);
-                    $email = trim(str_replace('>', '', $email));
-                    $name = trim($name);
-                    if (static::validateAddress($email)) {
-                        //Check for a Mbstring constant rather than using extension_loaded, which is sometimes disabled
-                        //If this name is encoded, decode it
-                        if (defined('MB_CASE_UPPER') && preg_match('/^=\?.*\?=$/s', $name)) {
-                            $origCharset = mb_internal_encoding();
-                            mb_internal_encoding($charset);
-                            //Undo any RFC2047-encoded spaces-as-underscores
-                            $name = str_replace('_', '=20', $name);
-                            //Decode the name
-                            $name = mb_decode_mimeheader($name);
-                            mb_internal_encoding($origCharset);
-                        }
-                        $addresses[] = [
-                            //Remove any surrounding quotes and spaces from the name
-                            'name' => trim($name, '\'" '),
-                            'address' => $email,
-                        ];
-                    }
+            $addresses = static::parseSimplerAddresses($addrstr, $charset);
+        }
+
+        return $addresses;
+    }
+
+    /**
+     * Parse a string containing one or more RFC822-style comma-separated email addresses
+     * with the form "display name <address>" into an array of name/address pairs.
+     * Uses a simpler parser that does not require the IMAP extension but doesnt support
+     * the full RFC822 spec. For full RFC822 support, use the PHP IMAP extension.
+     *
+     * @param string $addrstr The address list string
+     * @param string $charset The charset to use when decoding the address list string.
+     *
+     * @return array
+     */
+    protected static function parseSimplerAddresses($addrstr, $charset)
+    {
+        // Emit a runtime notice to recommend using the IMAP extension for full RFC822 parsing
+        trigger_error(self::lang('imap_recommended'), E_USER_NOTICE);
+
+        $addresses = [];
+        $list = explode(',', $addrstr);
+        foreach ($list as $address) {
+            $address = trim($address);
+            //Is there a separate name part?
+            if (strpos($address, '<') === false) {
+                //No separate name, just use the whole thing
+                if (static::validateAddress($address)) {
+                    $addresses[] = [
+                        'name' => '',
+                        'address' => $address,
+                    ];
+                }
+            } else {
+                $parsed = static::parseEmailString($address);
+                $email = $parsed['email'];
+                if (static::validateAddress($email)) {
+                    $name = static::decodeHeader($parsed['name'], $charset);
+                    $addresses[] = [
+                        //Remove any surrounding quotes and spaces from the name
+                        'name' => trim($name, '\'" '),
+                        'address' => $email,
+                    ];
                 }
             }
         }
@@ -1322,6 +1333,42 @@ class PHPMailer
     }
 
     /**
+     * Parse a string containing an email address with an optional name
+     * and divide it into a name and email address.
+     *
+     * @param string $input The email with name.
+     *
+     * @return array{name: string, email: string}
+     */
+    private static function parseEmailString($input)
+    {
+        $input = trim((string)$input);
+
+        if ($input === '') {
+            return ['name' => '', 'email' => ''];
+        }
+
+        $pattern = '/^\s*(?:(?:"([^"]*)"|\'([^\']*)\'|([^<]*?))\s*)?<\s*([^>]+)\s*>\s*$/';
+        if (preg_match($pattern, $input, $matches)) {
+            $name = '';
+            // Double quotes including special scenarios.
+            if (isset($matches[1]) && $matches[1] !== '') {
+                $name = $matches[1];
+            // Single quotes including special scenarios.
+            } elseif (isset($matches[2]) && $matches[2] !== '') {
+                $name = $matches[2];
+            // Simplest scenario, name and email are in the format "Name <email>".
+            } elseif (isset($matches[3])) {
+                $name = trim($matches[3]);
+            }
+
+            return ['name' => $name, 'email' => trim($matches[4])];
+        }
+
+        return ['name' => '', 'email' => $input];
+    }
+
+    /**
      * Set the From and FromName properties.
      *
      * @param string $address
@@ -1334,6 +1381,10 @@ class PHPMailer
      */
     public function setFrom($address, $name = '', $auto = true)
     {
+        if (is_null($name)) {
+            //Helps avoid a deprecation warning in the preg_replace() below
+            $name = '';
+        }
         $address = trim((string)$address);
         $name = trim(preg_replace('/[\r\n]+/', '', $name)); //Strip breaks and trim
         //Don't validate now addresses with IDN. Will be done in send().
@@ -1345,7 +1396,7 @@ class PHPMailer
         ) {
             $error_message = sprintf(
                 '%s (From): %s',
-                $this->lang('invalid_address'),
+                self::lang('invalid_address'),
                 $address
             );
             $this->setError($error_message);
@@ -1601,7 +1652,7 @@ class PHPMailer
             && ini_get('mail.add_x_header') === '1'
             && stripos(PHP_OS, 'WIN') === 0
         ) {
-            trigger_error($this->lang('buggy_php'), E_USER_WARNING);
+            trigger_error(self::lang('buggy_php'), E_USER_WARNING);
         }
 
         try {
@@ -1631,7 +1682,7 @@ class PHPMailer
                 call_user_func_array([$this, 'addAnAddress'], $params);
             }
             if (count($this->to) + count($this->cc) + count($this->bcc) < 1) {
-                throw new Exception($this->lang('provide_address'), self::STOP_CRITICAL);
+                throw new Exception(self::lang('provide_address'), self::STOP_CRITICAL);
             }
 
             //Validate From, Sender, and ConfirmReadingTo addresses
@@ -1648,7 +1699,7 @@ class PHPMailer
                 if (!static::validateAddress($this->{$address_kind})) {
                     $error_message = sprintf(
                         '%s (%s): %s',
-                        $this->lang('invalid_address'),
+                        self::lang('invalid_address'),
                         $address_kind,
                         $this->{$address_kind}
                     );
@@ -1670,7 +1721,7 @@ class PHPMailer
             $this->setMessageType();
             //Refuse to send an empty message unless we are specifically allowing it
             if (!$this->AllowEmpty && empty($this->Body)) {
-                throw new Exception($this->lang('empty_message'), self::STOP_CRITICAL);
+                throw new Exception(self::lang('empty_message'), self::STOP_CRITICAL);
             }
 
             //Trim subject consistently
@@ -1809,8 +1860,10 @@ class PHPMailer
             } else {
                 $sendmailFmt = '%s -oi -f%s -t';
             }
+        } elseif ($this->Mailer === 'qmail') {
+            $sendmailFmt = '%s';
         } else {
-            //allow sendmail to choose a default envelope sender. It may
+            //Allow sendmail to choose a default envelope sender. It may
             //seem preferable to force it to use the From header as with
             //SMTP, but that introduces new problems (see
             //<https://github.com/PHPMailer/PHPMailer/issues/2298>), and
@@ -1828,33 +1881,35 @@ class PHPMailer
             foreach ($this->SingleToArray as $toAddr) {
                 $mail = @popen($sendmail, 'w');
                 if (!$mail) {
-                    throw new Exception($this->lang('execute') . $this->Sendmail, self::STOP_CRITICAL);
+                    throw new Exception(self::lang('execute') . $this->Sendmail, self::STOP_CRITICAL);
                 }
                 $this->edebug("To: {$toAddr}");
                 fwrite($mail, 'To: ' . $toAddr . "\n");
                 fwrite($mail, $header);
                 fwrite($mail, $body);
                 $result = pclose($mail);
-                $addrinfo = static::parseAddresses($toAddr, true, $this->CharSet);
-                $this->doCallback(
-                    ($result === 0),
-                    [[$addrinfo['address'], $addrinfo['name']]],
-                    $this->cc,
-                    $this->bcc,
-                    $this->Subject,
-                    $body,
-                    $this->From,
-                    []
-                );
+                $addrinfo = static::parseAddresses($toAddr, null, $this->CharSet);
+                foreach ($addrinfo as $addr) {
+                    $this->doCallback(
+                        ($result === 0),
+                        [[$addr['address'], $addr['name']]],
+                        $this->cc,
+                        $this->bcc,
+                        $this->Subject,
+                        $body,
+                        $this->From,
+                        []
+                    );
+                }
                 $this->edebug("Result: " . ($result === 0 ? 'true' : 'false'));
                 if (0 !== $result) {
-                    throw new Exception($this->lang('execute') . $this->Sendmail, self::STOP_CRITICAL);
+                    throw new Exception(self::lang('execute') . $this->Sendmail, self::STOP_CRITICAL);
                 }
             }
         } else {
             $mail = @popen($sendmail, 'w');
             if (!$mail) {
-                throw new Exception($this->lang('execute') . $this->Sendmail, self::STOP_CRITICAL);
+                throw new Exception(self::lang('execute') . $this->Sendmail, self::STOP_CRITICAL);
             }
             fwrite($mail, $header);
             fwrite($mail, $body);
@@ -1871,7 +1926,7 @@ class PHPMailer
             );
             $this->edebug("Result: " . ($result === 0 ? 'true' : 'false'));
             if (0 !== $result) {
-                throw new Exception($this->lang('execute') . $this->Sendmail, self::STOP_CRITICAL);
+                throw new Exception(self::lang('execute') . $this->Sendmail, self::STOP_CRITICAL);
             }
         }
 
@@ -2010,17 +2065,19 @@ class PHPMailer
         if ($this->SingleTo && count($toArr) > 1) {
             foreach ($toArr as $toAddr) {
                 $result = $this->mailPassthru($toAddr, $this->Subject, $body, $header, $params);
-                $addrinfo = static::parseAddresses($toAddr, true, $this->CharSet);
-                $this->doCallback(
-                    $result,
-                    [[$addrinfo['address'], $addrinfo['name']]],
-                    $this->cc,
-                    $this->bcc,
-                    $this->Subject,
-                    $body,
-                    $this->From,
-                    []
-                );
+                $addrinfo = static::parseAddresses($toAddr, null, $this->CharSet);
+                foreach ($addrinfo as $addr) {
+                    $this->doCallback(
+                        $result,
+                        [[$addr['address'], $addr['name']]],
+                        $this->cc,
+                        $this->bcc,
+                        $this->Subject,
+                        $body,
+                        $this->From,
+                        []
+                    );
+                }
             }
         } else {
             $result = $this->mailPassthru($to, $this->Subject, $body, $header, $params);
@@ -2030,7 +2087,7 @@ class PHPMailer
             ini_set('sendmail_from', $old_from);
         }
         if (!$result) {
-            throw new Exception($this->lang('instantiate'), self::STOP_CRITICAL);
+            throw new Exception(self::lang('instantiate'), self::STOP_CRITICAL);
         }
 
         return true;
@@ -2116,12 +2173,12 @@ class PHPMailer
         $header = static::stripTrailingWSP($header) . static::$LE . static::$LE;
         $bad_rcpt = [];
         if (!$this->smtpConnect($this->SMTPOptions)) {
-            throw new Exception($this->lang('smtp_connect_failed'), self::STOP_CRITICAL);
+            throw new Exception(self::lang('smtp_connect_failed'), self::STOP_CRITICAL);
         }
         //If we have recipient addresses that need Unicode support,
         //but the server doesn't support it, stop here
         if ($this->UseSMTPUTF8 && !$this->smtp->getServerExt('SMTPUTF8')) {
-            throw new Exception($this->lang('no_smtputf8'), self::STOP_CRITICAL);
+            throw new Exception(self::lang('no_smtputf8'), self::STOP_CRITICAL);
         }
         //Sender already validated in preSend()
         if ('' === $this->Sender) {
@@ -2133,7 +2190,7 @@ class PHPMailer
             $this->smtp->xclient($this->SMTPXClient);
         }
         if (!$this->smtp->mail($smtp_from)) {
-            $this->setError($this->lang('from_failed') . $smtp_from . ' : ' . implode(',', $this->smtp->getError()));
+            $this->setError(self::lang('from_failed') . $smtp_from . ' : ' . implode(',', $this->smtp->getError()));
             throw new Exception($this->ErrorInfo, self::STOP_CRITICAL);
         }
 
@@ -2155,7 +2212,7 @@ class PHPMailer
 
         //Only send the DATA command if we have viable recipients
         if ((count($this->all_recipients) > count($bad_rcpt)) && !$this->smtp->data($header . $body)) {
-            throw new Exception($this->lang('data_not_accepted'), self::STOP_CRITICAL);
+            throw new Exception(self::lang('data_not_accepted'), self::STOP_CRITICAL);
         }
 
         $smtp_transaction_id = $this->smtp->getLastTransactionID();
@@ -2186,7 +2243,7 @@ class PHPMailer
             foreach ($bad_rcpt as $bad) {
                 $errstr .= $bad['to'] . ': ' . $bad['error'];
             }
-            throw new Exception($this->lang('recipients_failed') . $errstr, self::STOP_CONTINUE);
+            throw new Exception(self::lang('recipients_failed') . $errstr, self::STOP_CONTINUE);
         }
 
         return true;
@@ -2240,7 +2297,7 @@ class PHPMailer
                     $hostinfo
                 )
             ) {
-                $this->edebug($this->lang('invalid_hostentry') . ' ' . trim($hostentry));
+                $this->edebug(self::lang('invalid_hostentry') . ' ' . trim($hostentry));
                 //Not a valid host entry
                 continue;
             }
@@ -2252,7 +2309,7 @@ class PHPMailer
 
             //Check the host name is a valid name or IP address before trying to use it
             if (!static::isValidHost($hostinfo[2])) {
-                $this->edebug($this->lang('invalid_host') . ' ' . $hostinfo[2]);
+                $this->edebug(self::lang('invalid_host') . ' ' . $hostinfo[2]);
                 continue;
             }
             $prefix = '';
@@ -2272,7 +2329,7 @@ class PHPMailer
             if (static::ENCRYPTION_STARTTLS === $secure || static::ENCRYPTION_SMTPS === $secure) {
                 //Check for an OpenSSL constant rather than using extension_loaded, which is sometimes disabled
                 if (!$sslext) {
-                    throw new Exception($this->lang('extension_missing') . 'openssl', self::STOP_CRITICAL);
+                    throw new Exception(self::lang('extension_missing') . 'openssl', self::STOP_CRITICAL);
                 }
             }
             $host = $hostinfo[2];
@@ -2324,7 +2381,7 @@ class PHPMailer
                             $this->oauth
                         )
                     ) {
-                        throw new Exception($this->lang('authenticate'));
+                        throw new Exception(self::lang('authenticate'));
                     }
 
                     return true;
@@ -2374,7 +2431,7 @@ class PHPMailer
      *
      * @return bool Returns true if the requested language was loaded, false otherwise.
      */
-    public function setLanguage($langcode = 'en', $lang_path = '')
+    public static function setLanguage($langcode = 'en', $lang_path = '')
     {
         //Backwards compatibility for renamed language codes
         $renamed_langcodes = [
@@ -2423,6 +2480,9 @@ class PHPMailer
             'smtp_error' => 'SMTP server error: ',
             'variable_set' => 'Cannot set or reset variable: ',
             'no_smtputf8' => 'Server does not support SMTPUTF8 needed to send to Unicode addresses',
+            'imap_recommended' => 'Using simplified address parser is not recommended. ' .
+                'Install the PHP IMAP extension for full RFC822 parsing.',
+            'deprecated_argument' => 'Argument $useimap is deprecated',
         ];
         if (empty($lang_path)) {
             //Calculate an absolute path so it can work if CWD is not here
@@ -2489,7 +2549,7 @@ class PHPMailer
                 }
             }
         }
-        $this->language = $PHPMAILER_LANG;
+        self::$language = $PHPMAILER_LANG;
 
         return $foundlang; //Returns false if language not found
     }
@@ -2501,11 +2561,11 @@ class PHPMailer
      */
     public function getTranslations()
     {
-        if (empty($this->language)) {
-            $this->setLanguage(); // Set the default language.
+        if (empty(self::$language)) {
+            self::setLanguage(); // Set the default language.
         }
 
-        return $this->language;
+        return self::$language;
     }
 
     /**
@@ -2928,10 +2988,6 @@ class PHPMailer
         //Create unique IDs and preset boundaries
         $this->setBoundaries();
 
-        if ($this->sign_key_file) {
-            $body .= $this->getMailMIME() . static::$LE;
-        }
-
         $this->setWordWrap();
 
         $bodyEncoding = $this->Encoding;
@@ -2963,6 +3019,12 @@ class PHPMailer
         if (static::ENCODING_BASE64 !== $altBodyEncoding && static::hasLineLongerThanMax($this->AltBody)) {
             $altBodyEncoding = static::ENCODING_QUOTED_PRINTABLE;
         }
+
+        if ($this->sign_key_file) {
+            $this->Encoding = $bodyEncoding;
+            $body .= $this->getMailMIME() . static::$LE;
+        }
+
         //Use this as a preamble in all multipart message types
         $mimepre = '';
         switch ($this->message_type) {
@@ -3144,12 +3206,12 @@ class PHPMailer
         if ($this->isError()) {
             $body = '';
             if ($this->exceptions) {
-                throw new Exception($this->lang('empty_message'), self::STOP_CRITICAL);
+                throw new Exception(self::lang('empty_message'), self::STOP_CRITICAL);
             }
         } elseif ($this->sign_key_file) {
             try {
                 if (!defined('PKCS7_TEXT')) {
-                    throw new Exception($this->lang('extension_missing') . 'openssl');
+                    throw new Exception(self::lang('extension_missing') . 'openssl');
                 }
 
                 $file = tempnam(sys_get_temp_dir(), 'srcsign');
@@ -3187,7 +3249,7 @@ class PHPMailer
                     $body = $parts[1];
                 } else {
                     @unlink($signed);
-                    throw new Exception($this->lang('signing') . openssl_error_string());
+                    throw new Exception(self::lang('signing') . openssl_error_string());
                 }
             } catch (Exception $exc) {
                 $body = '';
@@ -3332,7 +3394,7 @@ class PHPMailer
     ) {
         try {
             if (!static::fileIsAccessible($path)) {
-                throw new Exception($this->lang('file_access') . $path, self::STOP_CONTINUE);
+                throw new Exception(self::lang('file_access') . $path, self::STOP_CONTINUE);
             }
 
             //If a MIME type is not specified, try to work it out from the file name
@@ -3345,7 +3407,7 @@ class PHPMailer
                 $name = $filename;
             }
             if (!$this->validateEncoding($encoding)) {
-                throw new Exception($this->lang('encoding') . $encoding);
+                throw new Exception(self::lang('encoding') . $encoding);
             }
 
             $this->attachment[] = [
@@ -3506,11 +3568,11 @@ class PHPMailer
     {
         try {
             if (!static::fileIsAccessible($path)) {
-                throw new Exception($this->lang('file_open') . $path, self::STOP_CONTINUE);
+                throw new Exception(self::lang('file_open') . $path, self::STOP_CONTINUE);
             }
             $file_buffer = file_get_contents($path);
             if (false === $file_buffer) {
-                throw new Exception($this->lang('file_open') . $path, self::STOP_CONTINUE);
+                throw new Exception(self::lang('file_open') . $path, self::STOP_CONTINUE);
             }
             $file_buffer = $this->encodeString($file_buffer, $encoding);
 
@@ -3563,9 +3625,9 @@ class PHPMailer
                 $encoded = $this->encodeQP($str);
                 break;
             default:
-                $this->setError($this->lang('encoding') . $encoding);
+                $this->setError(self::lang('encoding') . $encoding);
                 if ($this->exceptions) {
-                    throw new Exception($this->lang('encoding') . $encoding);
+                    throw new Exception(self::lang('encoding') . $encoding);
                 }
                 break;
         }
@@ -3672,6 +3734,42 @@ class PHPMailer
     }
 
     /**
+     * Decode an RFC2047-encoded header value
+     * Attempts multiple strategies so it works even when the mbstring extension is disabled.
+     *
+     * @param string $value   The header value to decode
+     * @param string $charset The target charset to convert to, defaults to ISO-8859-1 for BC
+     *
+     * @return string The decoded header value
+     */
+    public static function decodeHeader($value, $charset = self::CHARSET_ISO88591)
+    {
+        if (!is_string($value) || $value === '') {
+            return '';
+        }
+        // Detect the presence of any RFC2047 encoded-words
+        $hasEncodedWord = (bool) preg_match('/=\?.*\?=/s', $value);
+        if ($hasEncodedWord && defined('MB_CASE_UPPER')) {
+            $origCharset = mb_internal_encoding();
+            // Always decode to UTF-8 to provide a consistent, modern output encoding.
+            mb_internal_encoding($charset);
+            if (PHP_VERSION_ID < 80300) {
+                // Undo any RFC2047-encoded spaces-as-underscores.
+                $value = str_replace('_', '=20', $value);
+            } else {
+                // PHP 8.3+ already interprets underscores as spaces. Remove additional
+                // linear whitespace between adjacent encoded words to avoid double spacing.
+                $value = preg_replace('/(\?=)\s+(=\?)/', '$1$2', $value);
+            }
+            // Decode the header value
+            $value = mb_decode_mimeheader($value);
+            mb_internal_encoding($origCharset);
+        }
+
+        return $value;
+    }
+
+    /**
      * Check if a string contains multi-byte characters.
      *
      * @param string $str multi-byte text to wrap encode
@@ -3840,7 +3938,7 @@ class PHPMailer
             }
 
             if (!$this->validateEncoding($encoding)) {
-                throw new Exception($this->lang('encoding') . $encoding);
+                throw new Exception(self::lang('encoding') . $encoding);
             }
 
             //Append to $attachment array
@@ -3899,7 +3997,7 @@ class PHPMailer
     ) {
         try {
             if (!static::fileIsAccessible($path)) {
-                throw new Exception($this->lang('file_access') . $path, self::STOP_CONTINUE);
+                throw new Exception(self::lang('file_access') . $path, self::STOP_CONTINUE);
             }
 
             //If a MIME type is not specified, try to work it out from the file name
@@ -3908,7 +4006,7 @@ class PHPMailer
             }
 
             if (!$this->validateEncoding($encoding)) {
-                throw new Exception($this->lang('encoding') . $encoding);
+                throw new Exception(self::lang('encoding') . $encoding);
             }
 
             $filename = (string) static::mb_pathinfo($path, PATHINFO_BASENAME);
@@ -3974,7 +4072,7 @@ class PHPMailer
             }
 
             if (!$this->validateEncoding($encoding)) {
-                throw new Exception($this->lang('encoding') . $encoding);
+                throw new Exception(self::lang('encoding') . $encoding);
             }
 
             //Append to $attachment array
@@ -4231,7 +4329,7 @@ class PHPMailer
                 }
                 if (strpbrk($name . $value, "\r\n") !== false) {
                     if ($this->exceptions) {
-                        throw new Exception($this->lang('invalid_header'));
+                        throw new Exception(self::lang('invalid_header'));
                     }
 
                     return false;
@@ -4255,15 +4353,15 @@ class PHPMailer
         if ('smtp' === $this->Mailer && null !== $this->smtp) {
             $lasterror = $this->smtp->getError();
             if (!empty($lasterror['error'])) {
-                $msg .= ' ' . $this->lang('smtp_error') . $lasterror['error'];
+                $msg .= ' ' . self::lang('smtp_error') . $lasterror['error'];
                 if (!empty($lasterror['detail'])) {
-                    $msg .= ' ' . $this->lang('smtp_detail') . $lasterror['detail'];
+                    $msg .= ' ' . self::lang('smtp_detail') . $lasterror['detail'];
                 }
                 if (!empty($lasterror['smtp_code'])) {
-                    $msg .= ' ' . $this->lang('smtp_code') . $lasterror['smtp_code'];
+                    $msg .= ' ' . self::lang('smtp_code') . $lasterror['smtp_code'];
                 }
                 if (!empty($lasterror['smtp_code_ex'])) {
-                    $msg .= ' ' . $this->lang('smtp_code_ex') . $lasterror['smtp_code_ex'];
+                    $msg .= ' ' . self::lang('smtp_code_ex') . $lasterror['smtp_code_ex'];
                 }
             }
         }
@@ -4388,21 +4486,21 @@ class PHPMailer
      *
      * @return string
      */
-    protected function lang($key)
+    protected static function lang($key)
     {
-        if (count($this->language) < 1) {
-            $this->setLanguage(); //Set the default language
+        if (count(self::$language) < 1) {
+            self::setLanguage(); //Set the default language
         }
 
-        if (array_key_exists($key, $this->language)) {
+        if (array_key_exists($key, self::$language)) {
             if ('smtp_connect_failed' === $key) {
                 //Include a link to troubleshooting docs on SMTP connection failure.
                 //This is by far the biggest cause of support questions
                 //but it's usually not PHPMailer's fault.
-                return $this->language[$key] . ' https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting';
+                return self::$language[$key] . ' https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting';
             }
 
-            return $this->language[$key];
+            return self::$language[$key];
         }
 
         //Return the key as a fallback
@@ -4417,7 +4515,7 @@ class PHPMailer
      */
     private function getSmtpErrorMessage($base_key)
     {
-        $message = $this->lang($base_key);
+        $message = self::lang($base_key);
         $error = $this->smtp->getError();
         if (!empty($error['error'])) {
             $message .= ' ' . $error['error'];
@@ -4461,7 +4559,7 @@ class PHPMailer
         //Ensure name is not empty, and that neither name nor value contain line breaks
         if (empty($name) || strpbrk($name . $value, "\r\n") !== false) {
             if ($this->exceptions) {
-                throw new Exception($this->lang('invalid_header'));
+                throw new Exception(self::lang('invalid_header'));
             }
 
             return false;
@@ -4854,7 +4952,7 @@ class PHPMailer
 
             return true;
         }
-        $this->setError($this->lang('variable_set') . $name);
+        $this->setError(self::lang('variable_set') . $name);
 
         return false;
     }
@@ -4992,7 +5090,7 @@ class PHPMailer
     {
         if (!defined('PKCS7_TEXT')) {
             if ($this->exceptions) {
-                throw new Exception($this->lang('extension_missing') . 'openssl');
+                throw new Exception(self::lang('extension_missing') . 'openssl');
             }
 
             return '';
diff --git a/lib/phpmailer/phpmailer/src/SMTP.php b/lib/phpmailer/phpmailer/src/SMTP.php
index 7226ee93b..3772c94ad 100644
--- a/lib/phpmailer/phpmailer/src/SMTP.php
+++ b/lib/phpmailer/phpmailer/src/SMTP.php
@@ -35,7 +35,7 @@ class SMTP
      *
      * @var string
      */
-    const VERSION = '6.10.0';
+    const VERSION = '6.11.1';
 
     /**
      * SMTP line break constant.
@@ -205,6 +205,7 @@ class SMTP
         'Haraka' => '/[\d]{3} Message Queued \((.*)\)/',
         'ZoneMTA' => '/[\d]{3} Message queued as (.*)/',
         'Mailjet' => '/[\d]{3} OK queued as (.*)/',
+        'Gsmtp' => '/[\d]{3} 2\.0\.0 OK (.*) - gsmtp/',
     ];
 
     /**
@@ -633,10 +634,41 @@ class SMTP
                     return false;
                 }
                 $oauth = $OAuth->getOauth64();
-
-                //Start authentication
-                if (!$this->sendCommand('AUTH', 'AUTH XOAUTH2 ' . $oauth, 235)) {
-                    return false;
+                /*
+                 * An SMTP command line can have a maximum length of 512 bytes, including the command name,
+                 * so the base64-encoded OAUTH token has a maximum length of:
+                 * 512 - 13 (AUTH XOAUTH2) - 2 (CRLF) = 497 bytes
+                 * If the token is longer than that, the command and the token must be sent separately as described in
+                 * https://www.rfc-editor.org/rfc/rfc4954#section-4
+                 */
+                if ($oauth === '') {
+                    //Sending an empty auth token is legitimate, but it must be encoded as '='
+                    //to indicate it's not a 2-part command
+                    if (!$this->sendCommand('AUTH', 'AUTH XOAUTH2 =', 235)) {
+                        return false;
+                    }
+                } elseif (strlen($oauth) <= 497) {
+                    //Authenticate using a token in the initial-response part
+                    if (!$this->sendCommand('AUTH', 'AUTH XOAUTH2 ' . $oauth, 235)) {
+                        return false;
+                    }
+                } else {
+                    //The token is too long, so we need to send it in two parts.
+                    //Send the auth command without a token and expect a 334
+                    if (!$this->sendCommand('AUTH', 'AUTH XOAUTH2', 334)) {
+                        return false;
+                    }
+                    //Send the token
+                    if (!$this->sendCommand('OAuth TOKEN', $oauth, [235, 334])) {
+                        return false;
+                    }
+                    //If the server answers with 334, send an empty line and wait for a 235
+                    if (
+                        substr($this->last_reply, 0, 3) === '334'
+                        && $this->sendCommand('AUTH End', '', 235)
+                    ) {
+                        return false;
+                    }
                 }
                 break;
             default:
@@ -1309,7 +1341,16 @@ class SMTP
 
                 //stream_select returns false when the `select` system call is interrupted
                 //by an incoming signal, try the select again
-                if (stripos($message, 'interrupted system call') !== false) {
+                if (
+                    stripos($message, 'interrupted system call') !== false ||
+                    (
+                        // on applications with a different locale than english, the message above is not found because
+                        // it's translated. So we also check for the SOCKET_EINTR constant which is defined under
+                        // Windows and UNIX-like platforms (if available on the platform).
+                        defined('SOCKET_EINTR') &&
+                        stripos($message, 'stream_select(): Unable to select [' . SOCKET_EINTR . ']') !== false
+                    )
+                ) {
                     $this->edebug(
                         'SMTP -> get_lines(): retrying stream_select',
                         self::DEBUG_LOWLEVEL