diff --git a/extensions/mailer/runtime/src/main/java/io/quarkus/mailer/runtime/Mailers.java b/extensions/mailer/runtime/src/main/java/io/quarkus/mailer/runtime/Mailers.java
index 4239dd46abaac..ce3b238a4f32e 100644
--- a/extensions/mailer/runtime/src/main/java/io/quarkus/mailer/runtime/Mailers.java
+++ b/extensions/mailer/runtime/src/main/java/io/quarkus/mailer/runtime/Mailers.java
@@ -128,7 +128,8 @@ public void stop() {
 
     private MailClient createMailClient(Vertx vertx, MailerRuntimeConfig config, TlsConfig tlsConfig) {
         io.vertx.ext.mail.MailConfig cfg = toVertxMailConfig(config, tlsConfig);
-        return MailClient.createShared(vertx, cfg);
+        // Do not create a shared instance, as we want separated connection pool for each SMTP servers.
+        return MailClient.create(vertx, cfg);
     }
 
     private io.vertx.ext.mail.DKIMSignOptions toVertxDkimSignOptions(DkimSignOptionsConfig optionsConfig) {
diff --git a/integration-tests/virtual-threads/pom.xml b/integration-tests/virtual-threads/pom.xml
index 96fabdd34574b..f23f86a062baa 100644
--- a/integration-tests/virtual-threads/pom.xml
+++ b/integration-tests/virtual-threads/pom.xml
@@ -104,7 +104,7 @@
                             <maven.home>${maven.home}</maven.home>
                         </systemPropertyVariables>
                         <!-- gradle scan capture test logging disabled: System.out in virtual threads cause pinning when enabled. -->
-                        <argLine>-Djdk.tracePinnedThreads -Dgradle.scan.captureTestLogging=false</argLine>
+                        <argLine>--enable-preview -Djdk.tracePinnedThreads -Dgradle.scan.captureTestLogging=false</argLine>
                         <skipTests>${skipTests}</skipTests>
                     </configuration>
                 </plugin>
@@ -131,6 +131,7 @@
                     <version>${version.compiler.plugin}</version>
                     <configuration>
                         <compilerArgs>
+                            <arg>--enable-preview</arg>
                             <arg>-parameters</arg>
                         </compilerArgs>
                     </configuration>