diff --git a/composer.json b/composer.json
index 05b05c75..63d0ffd6 100644
--- a/composer.json
+++ b/composer.json
@@ -42,8 +42,8 @@
         "doctrine/annotations": "^1.2.6 || ^1.13.3",
         "php-parallel-lint/php-console-highlighter": "^1.0.0",
         "php-parallel-lint/php-parallel-lint": "^1.3.2",
-        "phpcompatibility/php-compatibility": "^9.3.5",
-        "squizlabs/php_codesniffer": "^3.7.2",
+        "phpcompatibility/php-compatibility": "^10.0.0@dev",
+        "squizlabs/php_codesniffer": "^3.13.5",
         "yoast/phpunit-polyfills": "^1.0.4"
     },
     "suggest": {
@@ -56,8 +56,11 @@
         "league/oauth2-google": "Needed for Google XOAUTH2 authentication",
         "psr/log": "For optional PSR-3 debug logging",
         "symfony/polyfill-mbstring": "To support UTF-8 if the Mbstring PHP extension is not enabled (^1.2)",
-        "thenetworg/oauth2-azure": "Needed for Microsoft XOAUTH2 authentication"
+        "thenetworg/oauth2-azure": "Needed for Microsoft XOAUTH2 authentication",
+        "directorytree/imapengine": "For uploading sent messages via IMAP, see gmail example"
     },
+    "minimum-stability": "dev",
+    "prefer-stable": true,
     "autoload": {
         "psr-4": {
             "PHPMailer\\PHPMailer\\": "src/"
diff --git a/examples/gmail.phps b/examples/gmail.phps
index fe6e09a9..35e49966 100644
--- a/examples/gmail.phps
+++ b/examples/gmail.phps
@@ -83,26 +83,24 @@ if (!$mail->send()) {
     echo 'Message sent!';
     //Section 2: IMAP
     //Uncomment these to save your message in the 'Sent Mail' folder.
-    #if (save_mail($mail)) {
-    #    echo "Message saved!";
-    #}
+    #save_mail($mail->getSentMIMEMessage());
 }
 
 //Section 2: IMAP
-//IMAP commands requires the PHP IMAP Extension, found at: https://php.net/manual/en/imap.setup.php
-//Function to call which uses the PHP imap_*() functions to save messages: https://php.net/manual/en/book.imap.php
-//You can use imap_getmailboxes($imapStream, '/imap/ssl', '*' ) to get a list of available folders or labels, this can
-//be useful if you are trying to get this working on a non-Gmail IMAP server.
-function save_mail($mail)
+//This example uses the directorytree/imapengine IMAP library: https://imapengine.com
+//Earlier versions of this code used the deprecated PHP imap_* functions.
+function save_mail($message)
 {
-    //You can change 'Sent Mail' to any other folder or tag
-    $path = '{imap.gmail.com:993/imap/ssl}[Gmail]/Sent Mail';
+    $mailbox = new \DirectoryTree\ImapEngine\Mailbox([
+        'host' => 'imap.gmail.com',
+        'port' => 993,
+        'encryption' => 'ssl',
+        'username' => 'user@example.com',
+        'password' => 'password',
+    ]);
 
-    //Tell your server to open an IMAP connection using the same username and password as you used for SMTP
-    $imapStream = imap_open($path, $mail->Username, $mail->Password);
+    // Find the "sent" messages folder – yours may have a different name.
+    $folder = $mailbox->folders()->find('Sent Mail');
 
-    $result = imap_append($imapStream, $path, $mail->getSentMIMEMessage());
-    imap_close($imapStream);
-
-    return $result;
+    $folder->messages()->append($message);
 }
diff --git a/examples/mailing_list.phps b/examples/mailing_list.phps
index 4a536e7c..9eb05d63 100644
--- a/examples/mailing_list.phps
+++ b/examples/mailing_list.phps
@@ -8,7 +8,7 @@
 use PHPMailer\PHPMailer\PHPMailer;
 use PHPMailer\PHPMailer\Exception;
 
-error_reporting(E_STRICT | E_ALL);
+error_reporting(E_ALL);
 
 date_default_timezone_set('Etc/UTC');
 
@@ -51,7 +51,10 @@ foreach ($result as $row) {
     try {
         $mail->addAddress($row['email'], $row['full_name']);
     } catch (Exception $e) {
-        echo 'Invalid address skipped: ' . htmlspecialchars($row['email']) . '<br>';
+        printf(
+            'Invalid address skipped: %s<br>',
+            htmlspecialchars($row['email'], ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401)
+        );
         continue;
     }
     if (!empty($row['photo'])) {
@@ -66,8 +69,11 @@ foreach ($result as $row) {
 
     try {
         $mail->send();
-        echo 'Message sent to :' . htmlspecialchars($row['full_name']) . ' (' .
-            htmlspecialchars($row['email']) . ')<br>';
+        printf(
+            'Message sent to : %s (%s)<br>',
+            htmlspecialchars($row['full_name'], ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401),
+            htmlspecialchars($row['email'], ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401)
+        );
         //Mark it as sent in the DB
         mysqli_query(
             $mysql,
@@ -75,7 +81,11 @@ foreach ($result as $row) {
             mysqli_real_escape_string($mysql, $row['email']) . "'"
         );
     } catch (Exception $e) {
-        echo 'Mailer Error (' . htmlspecialchars($row['email']) . ') ' . $mail->ErrorInfo . '<br>';
+        printf(
+            'Mailer Error (%s) %s<br>',
+            htmlspecialchars($row['email'], ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401),
+            $mail->ErrorInfo
+        );
         //Reset the connection to abort sending this message
         //The loop will continue trying to send to the rest of the list
         $mail->getSMTPInstance()->reset();
diff --git a/examples/send_file_upload.phps b/examples/send_file_upload.phps
index 31d22837..8c6ec070 100644
--- a/examples/send_file_upload.phps
+++ b/examples/send_file_upload.phps
@@ -54,7 +54,7 @@ if (array_key_exists('userfile', $_FILES)) {
         <input type="submit" value="Send File">
     </form>
 <?php } else {
-    echo htmlspecialchars($msg);
+    echo htmlspecialchars($msg, ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401);
 } ?>
 </body>
 </html>
diff --git a/examples/send_multiple_file_upload.phps b/examples/send_multiple_file_upload.phps
index aeb65c14..e892ecb5 100644
--- a/examples/send_multiple_file_upload.phps
+++ b/examples/send_multiple_file_upload.phps
@@ -54,7 +54,7 @@ if (array_key_exists('userfile', $_FILES)) {
         <input type="submit" value="Send Files">
     </form>
 <?php } else {
-    echo htmlspecialchars($msg);
+    echo htmlspecialchars($msg, ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401);
 } ?>
 </body>
 </html>
diff --git a/get_oauth_token.php b/get_oauth_token.php
index 0e54a00b..9342b9c7 100644
--- a/get_oauth_token.php
+++ b/get_oauth_token.php
@@ -178,5 +178,5 @@ if (!isset($_GET['code'])) {
     );
     //Use this to interact with an API on the users behalf
     //Use this to get a new access token if the old one expires
-    echo 'Refresh Token: ', htmlspecialchars($token->getRefreshToken());
+    echo 'Refresh Token: ', htmlspecialchars($token->getRefreshToken(), ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401);
 }
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
index e2d1e5c6..bf51a72c 100644
--- a/phpcs.xml.dist
+++ b/phpcs.xml.dist
@@ -27,14 +27,7 @@
         <exclude name="PSR2.Methods.MethodDeclaration.Underscore"/>
         <exclude name="PSR12.Properties.ConstantVisibility.NotFound"/>
     </rule>
-    <rule ref="PHPCompatibility">
-        <exclude name="PHPCompatibility.Constants.NewConstants.stream_crypto_method_tlsv1_1_clientFound"/>
-        <exclude name="PHPCompatibility.Constants.NewConstants.stream_crypto_method_tlsv1_2_clientFound"/>
-        <exclude name="PHPCompatibility.Constants.RemovedConstants.intl_idna_variant_2003Deprecated"/>
-        <exclude name="PHPCompatibility.FunctionUse.NewFunctions.random_bytesFound"/>
-        <exclude name="PHPCompatibility.IniDirectives.RemovedIniDirectives.mbstring_func_overloadDeprecated"/>
-        <exclude name="PHPCompatibility.ParameterValues.NewIDNVariantDefault.NotSet"/>
-    </rule>
+    <rule ref="PHPCompatibility"/>
 
 
     <!--
diff --git a/src/PHPMailer.php b/src/PHPMailer.php
index 91512c43..bd9825f3 100644
--- a/src/PHPMailer.php
+++ b/src/PHPMailer.php
@@ -876,6 +876,7 @@ class PHPMailer
     private function mailPassthru($to, $subject, $body, $header, $params)
     {
         //Check overloading of mail function to avoid double-encoding
+        // phpcs:ignore PHPCompatibility.IniDirectives.RemovedIniDirectives.mbstring_func_overloadDeprecatedRemoved
         if ((int)ini_get('mbstring.func_overload') & 1) {
             $subject = $this->secureHeader($subject);
         } else {
@@ -1257,8 +1258,10 @@ class PHPMailer
         $addresses = [];
         if (function_exists('imap_rfc822_parse_adrlist')) {
             //Use this built-in parser if it's available
+            // phpcs:ignore PHPCompatibility.FunctionUse.RemovedFunctions.imap_rfc822_parse_adrlistRemoved -- wrapped in function_exists()
             $list = imap_rfc822_parse_adrlist($addrstr, '');
             // Clear any potential IMAP errors to get rid of notices being thrown at end of script.
+            // phpcs:ignore PHPCompatibility.FunctionUse.RemovedFunctions.imap_errorsRemoved -- wrapped in function_exists()
             imap_errors();
             foreach ($list as $address) {
                 if (
@@ -1585,9 +1588,11 @@ class PHPMailer
                     );
                 } elseif (defined('INTL_IDNA_VARIANT_2003')) {
                     //Fall back to this old, deprecated/removed encoding
+                    // phpcs:ignore PHPCompatibility.Constants.RemovedConstants.intl_idna_variant_2003DeprecatedRemoved
                     $punycode = idn_to_ascii($domain, $errorcode, \INTL_IDNA_VARIANT_2003);
                 } else {
                     //Fall back to a default we don't know about
+                    // phpcs:ignore PHPCompatibility.ParameterValues.NewIDNVariantDefault.NotSet
                     $punycode = idn_to_ascii($domain, $errorcode);
                 }
                 if (false !== $punycode) {
@@ -2958,6 +2963,7 @@ class PHPMailer
         $bytes = '';
         if (function_exists('random_bytes')) {
             try {
+                // phpcs:ignore PHPCompatibility.FunctionUse.NewFunctions.random_bytesFound -- Wrapped in function_exists.
                 $bytes = random_bytes($len);
             } catch (\Exception $e) {
                 //Do nothing
@@ -5113,12 +5119,14 @@ class PHPMailer
         }
         if (openssl_sign($signHeader, $signature, $privKey, 'sha256WithRSAEncryption')) {
             if (\PHP_MAJOR_VERSION < 8) {
+                // phpcs:ignore PHPCompatibility.FunctionUse.RemovedFunctions.openssl_pkey_freeDeprecated
                 openssl_pkey_free($privKey);
             }
 
             return base64_encode($signature);
         }
         if (\PHP_MAJOR_VERSION < 8) {
+            // phpcs:ignore PHPCompatibility.FunctionUse.RemovedFunctions.openssl_pkey_freeDeprecated
             openssl_pkey_free($privKey);
         }
 
diff --git a/src/SMTP.php b/src/SMTP.php
index 9bf6135a..c3fb54cb 100644
--- a/src/SMTP.php
+++ b/src/SMTP.php
@@ -494,7 +494,9 @@ class SMTP
         //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')) {
+            // phpcs:ignore PHPCompatibility.Constants.NewConstants.stream_crypto_method_tlsv1_2_clientFound
             $crypto_method |= STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT;
+            // phpcs:ignore PHPCompatibility.Constants.NewConstants.stream_crypto_method_tlsv1_1_clientFound
             $crypto_method |= STREAM_CRYPTO_METHOD_TLSv1_1_CLIENT;
         }
 
diff --git a/test/Fixtures/LocalizationTest/phpmailer.lang-yz.php b/test/Fixtures/LocalizationTest/phpmailer.lang-yz.php
index 2b0f8aa3..1d190b4b 100644
--- a/test/Fixtures/LocalizationTest/phpmailer.lang-yz.php
+++ b/test/Fixtures/LocalizationTest/phpmailer.lang-yz.php
@@ -8,6 +8,8 @@
  * Note: this test fixture uses a syntax (backticks) which has been deprecated in PHP 8.5 and
  * is slated for removal in PHP 9.0.
  * For that reason, the file is excluded from the linting check on PHP 8.5 and above.
+ *
+ * @phpcs:disable PHPCompatibility.LanguageConstructs.RemovedLanguageConstructs.t_backtickDeprecated
  */
 
 $PHPMAILER_LANG['extension_missing'] = 'Confirming that test fixture was loaded correctly (yz).';