diff --git a/src/PHPMailer.php b/src/PHPMailer.php
index 47dd3022..5444ab39 100644
--- a/src/PHPMailer.php
+++ b/src/PHPMailer.php
@@ -1122,19 +1122,22 @@ class PHPMailer
         $params = [$kind, $address, $name];
         //Enqueue addresses with IDN until we know the PHPMailer::$CharSet.
         //Domain is assumed to be whatever is after the last @ symbol in the address
-        if (static::idnSupported() && $this->has8bitChars(substr($address, ++$pos))) {
-            if ('Reply-To' !== $kind) {
-                if (!array_key_exists($address, $this->RecipientsQueue)) {
-                    $this->RecipientsQueue[$address] = $params;
+        if ($this->has8bitChars(substr($address, ++$pos))) {
+            if (static::idnSupported()) {
+                if ('Reply-To' !== $kind) {
+                    if (!array_key_exists($address, $this->RecipientsQueue)) {
+                        $this->RecipientsQueue[$address] = $params;
+
+                        return true;
+                    }
+                } elseif (!array_key_exists($address, $this->ReplyToQueue)) {
+                    $this->ReplyToQueue[$address] = $params;
 
                     return true;
                 }
-            } elseif (!array_key_exists($address, $this->ReplyToQueue)) {
-                $this->ReplyToQueue[$address] = $params;
-
-                return true;
             }
-
+            //We have an 8-bit domain, but we are missing the necessary extensions to support it
+            //Or we are already sending to this address
             return false;
         }
 
diff --git a/test/PHPMailer/DKIMTest.php b/test/PHPMailer/DKIMTest.php
index 34991846..c41afa1e 100644
--- a/test/PHPMailer/DKIMTest.php
+++ b/test/PHPMailer/DKIMTest.php
@@ -248,7 +248,7 @@ final class DKIMTest extends SendTestCase
     public function testDKIMSignOpenSSLNotAvailableException()
     {
         if (extension_loaded('openssl')) {
-            $this->markTestSkipped('Test requires OpenSSL *not* to be available');
+            self::markTestSkipped('Test requires OpenSSL *not* to be available');
         }
 
         $this->expectException(Exception::class);
diff --git a/test/PHPMailer/DKIMWithoutExceptionsTest.php b/test/PHPMailer/DKIMWithoutExceptionsTest.php
index 6e8429bb..4a7008b0 100644
--- a/test/PHPMailer/DKIMWithoutExceptionsTest.php
+++ b/test/PHPMailer/DKIMWithoutExceptionsTest.php
@@ -38,7 +38,7 @@ final class DKIMWithoutExceptionsTest extends TestCase
     public function testDKIMSignOpenSSLNotAvailable()
     {
         if (extension_loaded('openssl')) {
-            $this->markTestSkipped('Test requires OpenSSL *not* to be available');
+            self::markTestSkipped('Test requires OpenSSL *not* to be available');
         }
 
         $signature = $this->Mail->DKIM_Sign('foo');
diff --git a/test/PHPMailer/FileIsAccessibleTest.php b/test/PHPMailer/FileIsAccessibleTest.php
index 1dfa2e21..8989643a 100644
--- a/test/PHPMailer/FileIsAccessibleTest.php
+++ b/test/PHPMailer/FileIsAccessibleTest.php
@@ -83,7 +83,7 @@ final class FileIsAccessibleTest extends TestCase
     {
         if (\DIRECTORY_SEPARATOR === '\\') {
             // Windows does not respect chmod permissions.
-            $this->markTestSkipped('This test requires a non-Windows OS.');
+            self::markTestSkipped('This test requires a non-Windows OS.');
         }
 
         $path = dirname(__DIR__) . '/Fixtures/FileIsAccessibleTest/';
diff --git a/test/PHPMailer/ParseAddressesTest.php b/test/PHPMailer/ParseAddressesTest.php
index 9b20cb67..f6188b90 100644
--- a/test/PHPMailer/ParseAddressesTest.php
+++ b/test/PHPMailer/ParseAddressesTest.php
@@ -102,7 +102,7 @@ final class ParseAddressesTest extends TestCase
     public function testAddressSplittingNativeNoMbstring($addrstr, $expected, $charset = null)
     {
         if (extension_loaded('mbstring')) {
-            $this->markTestSkipped('Test requires MbString *not* to be available');
+            self::markTestSkipped('Test requires MbString *not* to be available');
         }
 
         if (isset($charset)) {
@@ -136,7 +136,7 @@ final class ParseAddressesTest extends TestCase
     public function testAddressSplittingImapNoMbstring($addrstr, $expected, $charset = null)
     {
         if (extension_loaded('mbstring')) {
-            $this->markTestSkipped('Test requires MbString *not* to be available');
+            self::markTestSkipped('Test requires MbString *not* to be available');
         }
 
         if (isset($charset)) {
diff --git a/test/PHPMailer/ReplyToGetSetClearTest.php b/test/PHPMailer/ReplyToGetSetClearTest.php
index 97212b89..993abdd0 100644
--- a/test/PHPMailer/ReplyToGetSetClearTest.php
+++ b/test/PHPMailer/ReplyToGetSetClearTest.php
@@ -409,7 +409,7 @@ final class ReplyToGetSetClearTest extends PreSendTestCase
     public function testAddReplyToFailsOn8BitCharInDomainWithoutOptionalExtensions()
     {
         if (PHPMailer::idnSupported()) {
-            $this->markTestSkipped('Test requires MbString and/or Intl *not* to be available');
+            self::markTestSkipped('Test requires MbString and/or Intl *not* to be available');
         }
 
         self::assertFalse($this->Mail->addReplyTo('test@françois.ch'));
diff --git a/test/PHPMailer/SetFromTest.php b/test/PHPMailer/SetFromTest.php
index 8d46fb26..d1a8f2bd 100644
--- a/test/PHPMailer/SetFromTest.php
+++ b/test/PHPMailer/SetFromTest.php
@@ -194,7 +194,7 @@ final class SetFromTest extends TestCase
     public function testSetFromFailsOn8BitCharInDomainWithoutOptionalExtensions()
     {
         if (extension_loaded('mbstring') && function_exists('idn_to_ascii')) {
-            $this->markTestSkipped('Test requires MbString and/or Intl *not* to be available');
+            self::markTestSkipped('Test requires MbString and/or Intl *not* to be available');
         }
 
         $this->testSetFromFail("8bit@ex\x80mple.com");
diff --git a/test/POP3/PopBeforeSmtpTest.php b/test/POP3/PopBeforeSmtpTest.php
index 3513ada9..5b3d4f06 100644
--- a/test/POP3/PopBeforeSmtpTest.php
+++ b/test/POP3/PopBeforeSmtpTest.php
@@ -52,7 +52,7 @@ final class PopBeforeSmtpTest extends TestCase
     protected function set_up()
     {
         if (DIRECTORY_SEPARATOR === '\\') {
-            $this->markTestSkipped('This test needs a non-Windows OS to run');
+            self::markTestSkipped('This test needs a non-Windows OS to run');
         }
 
         // Chdir to test directory as runfakepopserver.sh runs fakepopserver.sh