diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index ce7a7c88..18808995 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -116,7 +116,7 @@ jobs:
         with:
           php-version: ${{ matrix.php }}
           coverage: ${{ steps.set_cov.outputs.COV }}
-          ini-values: sendmail_path=/usr/sbin/sendmail -t -i, zend.multibyte=1, zend.script_encoding=UTF-8, default_charset=UTF-8, error_reporting=E_ALL, display_errors=On
+          ini-values: sendmail_path=/usr/sbin/sendmail -t -i, error_reporting=E_ALL, display_errors=On
           extensions: imap, mbstring, intl, ctype, filter, hash
 
       # Install dependencies and handle caching in one go.
diff --git a/src/PHPMailer.php b/src/PHPMailer.php
index d8d8bd45..3f11d93b 100644
--- a/src/PHPMailer.php
+++ b/src/PHPMailer.php
@@ -1188,7 +1188,7 @@ class PHPMailer
      *
      * @return array
      */
-    public static function parseAddresses($addrstr, $useimap = true)
+    public static function parseAddresses($addrstr, $useimap = true, $charset = self::CHARSET_ISO88591)
     {
         $addresses = [];
         if ($useimap && function_exists('imap_rfc822_parse_adrlist')) {
@@ -1209,7 +1209,10 @@ class PHPMailer
                         defined('MB_CASE_UPPER') &&
                         preg_match('/^=\?.*\?=$/', $address->personal)
                     ) {
+                        $origCharset = mb_internal_encoding();
+                        mb_internal_encoding($charset);
                         $address->personal = mb_decode_mimeheader($address->personal);
+                        mb_internal_encoding($origCharset);
                     }
 
                     $addresses[] = [
@@ -1240,7 +1243,10 @@ class PHPMailer
                         //Check for a Mbstring constant rather than using extension_loaded, which is sometimes disabled
                         //If this name is encoded, decode it
                         if (defined('MB_CASE_UPPER') && preg_match('/^=\?.*\?=$/', $name)) {
+                            $origCharset = mb_internal_encoding();
+                            mb_internal_encoding($charset);
                             $name = mb_decode_mimeheader($name);
+                            mb_internal_encoding($origCharset);
                         }
                         $addresses[] = [
                             //Remove any surrounding quotes and spaces from the name
@@ -1723,7 +1729,7 @@ class PHPMailer
                 fwrite($mail, $header);
                 fwrite($mail, $body);
                 $result = pclose($mail);
-                $addrinfo = static::parseAddresses($toAddr);
+                $addrinfo = static::parseAddresses($toAddr, true, $this->charSet);
                 $this->doCallback(
                     ($result === 0),
                     [[$addrinfo['address'], $addrinfo['name']]],
@@ -1883,7 +1889,7 @@ class PHPMailer
         if ($this->SingleTo && count($toArr) > 1) {
             foreach ($toArr as $toAddr) {
                 $result = $this->mailPassthru($toAddr, $this->Subject, $body, $header, $params);
-                $addrinfo = static::parseAddresses($toAddr);
+                $addrinfo = static::parseAddresses($toAddr, true, $this->charSet);
                 $this->doCallback(
                     $result,
                     [[$addrinfo['address'], $addrinfo['name']]],
diff --git a/test/PHPMailer/ParseAddressesTest.php b/test/PHPMailer/ParseAddressesTest.php
index 1bc6ec65..6f08a7f4 100644
--- a/test/PHPMailer/ParseAddressesTest.php
+++ b/test/PHPMailer/ParseAddressesTest.php
@@ -19,6 +19,11 @@ use Yoast\PHPUnitPolyfills\TestCases\TestCase;
 /**
  * Test RFC822 address splitting.
  *
+ * @todo Additional tests need to be added to verify the correct handling of inputs which
+ * include a different encoding than UTF8 or even mixed encoding. For more information
+ * on what these test cases should look like and should test, please see
+ * {@link https://github.com/PHPMailer/PHPMailer/pull/2449} for context.
+ *
  * @covers \PHPMailer\PHPMailer\PHPMailer::parseAddresses
  */
 final class ParseAddressesTest extends TestCase
@@ -34,10 +39,16 @@ final class ParseAddressesTest extends TestCase
      *
      * @param string $addrstr  The address list string.
      * @param array  $expected The expected function output.
+     * @param string $charset  Optional. The charset to use.
      */
-    public function testAddressSplittingNative($addrstr, $expected)
+    public function testAddressSplittingNative($addrstr, $expected, $charset = null)
     {
-        $parsed         = PHPMailer::parseAddresses($addrstr, false);
+        if (isset($charset)) {
+            $parsed = PHPMailer::parseAddresses($addrstr, false, $charset);
+        } else {
+            $parsed = PHPMailer::parseAddresses($addrstr, false);
+        }
+
         $expectedOutput = $expected['default'];
         if (empty($expected['native+mbstring']) === false) {
             $expectedOutput = $expected['native+mbstring'];
@@ -59,10 +70,16 @@ final class ParseAddressesTest extends TestCase
      *
      * @param string $addrstr  The address list string.
      * @param array  $expected The expected function output.
+     * @param string $charset  Optional. The charset to use.
      */
-    public function testAddressSplittingImap($addrstr, $expected)
+    public function testAddressSplittingImap($addrstr, $expected, $charset = null)
     {
-        $parsed         = PHPMailer::parseAddresses($addrstr, true);
+        if (isset($charset)) {
+            $parsed = PHPMailer::parseAddresses($addrstr, true, $charset);
+        } else {
+            $parsed = PHPMailer::parseAddresses($addrstr, true);
+        }
+
         $expectedOutput = $expected['default'];
         if (empty($expected['imap+mbstring']) === false) {
             $expectedOutput = $expected['imap+mbstring'];
@@ -81,14 +98,20 @@ final class ParseAddressesTest extends TestCase
      *
      * @param string $addrstr  The address list string.
      * @param array  $expected The expected function output.
+     * @param string $charset  Optional. The charset to use.
      */
-    public function testAddressSplittingNativeNoMbstring($addrstr, $expected)
+    public function testAddressSplittingNativeNoMbstring($addrstr, $expected, $charset = null)
     {
         if (extension_loaded('mbstring')) {
             $this->markTestSkipped('Test requires MbString *not* to be available');
         }
 
-        $parsed         = PHPMailer::parseAddresses($addrstr, false);
+        if (isset($charset)) {
+            $parsed = PHPMailer::parseAddresses($addrstr, false, $charset);
+        } else {
+            $parsed = PHPMailer::parseAddresses($addrstr, false);
+        }
+
         $expectedOutput = $expected['default'];
         if (empty($expected['native--mbstring']) === false) {
             $expectedOutput = $expected['native--mbstring'];
@@ -109,14 +132,20 @@ final class ParseAddressesTest extends TestCase
      *
      * @param string $addrstr  The address list string.
      * @param array  $expected The expected function output.
+     * @param string $charset  Optional. The charset to use.
      */
-    public function testAddressSplittingImapNoMbstring($addrstr, $expected)
+    public function testAddressSplittingImapNoMbstring($addrstr, $expected, $charset = null)
     {
         if (extension_loaded('mbstring')) {
             $this->markTestSkipped('Test requires MbString *not* to be available');
         }
 
-        $parsed         = PHPMailer::parseAddresses($addrstr, true);
+        if (isset($charset)) {
+            $parsed = PHPMailer::parseAddresses($addrstr, true, $charset);
+        } else {
+            $parsed = PHPMailer::parseAddresses($addrstr, true);
+        }
+
         $expectedOutput = $expected['default'];
         if (empty($expected['imap--mbstring']) === false) {
             $expectedOutput = $expected['imap--mbstring'];
@@ -157,6 +186,7 @@ final class ParseAddressesTest extends TestCase
      *               - `imap`             Expected output from the IMAP implementation with or without Mbstring.
      *               - `imap+mbstring`    Expected output from the IMAP implementation with Mbstring.
      *               - `imap--mbstring`   Expected output from the IMAP implementation without Mbstring.
+     *               Also optionally, an additional `charset` key can be passed,
      */
     public function dataAddressSplitting()
     {
@@ -282,6 +312,7 @@ final class ParseAddressesTest extends TestCase
                         ],
                     ],
                 ],
+                'charset' => PHPMailer::CHARSET_UTF8,
             ],
 
             // Test cases with invalid addresses.