diff --git a/api/src/main/java/jakarta/mail/Session.java b/api/src/main/java/jakarta/mail/Session.java
index c1476a66..bdcddcc0 100644
--- a/api/src/main/java/jakarta/mail/Session.java
+++ b/api/src/main/java/jakarta/mail/Session.java
@@ -36,6 +36,7 @@
 import java.security.PrivilegedActionException;
 import java.security.PrivilegedExceptionAction;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Hashtable;
@@ -1384,30 +1385,47 @@ EventQueue getEventQueue() {
         return q;
     }
 
-    private static final String OSGI_SERVICE_LOADER_CLASS_NAME = "org.glassfish.hk2.osgiresourcelocator.ServiceLoader";
-
-    @SuppressWarnings({"unchecked"})
-    private <T> Iterator<T> lookupUsingHk2ServiceLoader(Class<T> factoryId, ClassLoader loader) {
-        Class<?> target;
-        try {
-            target = Class.forName(OSGI_SERVICE_LOADER_CLASS_NAME, false, loader);
-        } catch (ClassNotFoundException ignored) {
-            return Collections.emptyIterator();
+    private static Class<?>[] getHk2ServiceLoaderTargets(Class<?> factoryClass) {
+        ClassLoader[] loaders = new ClassLoader[]{
+                Thread.currentThread().getContextClassLoader(), 
+                    factoryClass.getClassLoader(), 
+                    ClassLoader.getSystemClassLoader()};
+        
+        Class<?>[] classes = new Class<?>[loaders.length];
+        int w = 0;
+        for (ClassLoader loader : loaders) {
+            if (loader != null) {
+                try {
+                    classes[w++] = Class.forName("org.glassfish.hk2.osgiresourcelocator.ServiceLoader", false, loader);
+                } catch (ClassNotFoundException | LinkageError ignored) {  
+                }
+            }
         }
         
-        try {
-            // Use reflection to avoid having any dependency on HK2 ServiceLoader class
-            Class<?> serviceClass = Class.forName(factoryId.getName(), false, loader);
-            Class<?>[] args = new Class<?>[]{serviceClass};
-            Method m = target.getMethod("lookupProviderInstances", Class.class);
-            Iterable<T> result = ((Iterable<T>) m.invoke(null, (Object[]) args));
-            return result != null ? result.iterator() : Collections.emptyIterator();
-        } catch (Exception ignored) {
-            // log and continue
-            return Collections.emptyIterator();
+        if (classes.length != w) {
+           classes = Arrays.copyOf(classes, w);
         }
+        return classes;
     }
 
+    @SuppressWarnings({"unchecked"})
+    private <T> Iterator<T> lookupUsingHk2ServiceLoader(Class<T> factoryId, ClassLoader loader) {
+        for (Class<?> target : getHk2ServiceLoaderTargets(factoryId)) {
+            try {
+                // Use reflection to avoid having any dependency on HK2 ServiceLoader class
+                Class<?> serviceClass = Class.forName(factoryId.getName(), false, loader);
+                Class<?>[] args = new Class<?>[]{serviceClass};
+                Method m = target.getMethod("lookupProviderInstances", Class.class);
+                Iterable<T> result = ((Iterable<T>) m.invoke(null, (Object[]) args));
+                if (result != null) {
+                    return result.iterator();
+                }
+            } catch (Exception ignored) {
+                // log and continue
+            }
+        }
+        return Collections.emptyIterator();
+    }
 }
 
 /**
diff --git a/api/src/main/java/jakarta/mail/util/FactoryFinder.java b/api/src/main/java/jakarta/mail/util/FactoryFinder.java
index 838f503d..05658463 100644
--- a/api/src/main/java/jakarta/mail/util/FactoryFinder.java
+++ b/api/src/main/java/jakarta/mail/util/FactoryFinder.java
@@ -17,6 +17,7 @@
 package jakarta.mail.util;
 
 import java.lang.reflect.Method;
+import java.util.Arrays;
 import java.util.Iterator;
 import java.util.ServiceLoader;
 
@@ -34,16 +35,24 @@ class FactoryFinder {
      */
     static <T> T find(Class<T> factoryClass) throws RuntimeException {
         T result;
-        result = find(factoryClass, Thread.currentThread().getContextClassLoader());
-        if (result != null) {
-            return result;
+        ClassLoader loader = Thread.currentThread().getContextClassLoader();
+        if (loader != null) {
+            result = find(factoryClass, loader);
+            if (result != null) {
+                return result;
+            }
         }
 
-        result = find(factoryClass, factoryClass.getClassLoader());
-        if (result != null) {
-            return result;
+        //JakartaMail API ClassLoader / caller classloader
+        loader = factoryClass.getClassLoader();
+        if (loader != null) {
+            result = find(factoryClass, loader);
+            if (result != null) {
+                return result;
+            }
         }
 
+        //Fallback to system class loader
         result = find(factoryClass, ClassLoader.getSystemClassLoader());
         if (result != null) {
             return result;
@@ -53,10 +62,8 @@ static <T> T find(Class<T> factoryClass) throws RuntimeException {
     }
 
     private static <T> T find(Class<T> factoryClass, ClassLoader loader) throws RuntimeException {
-        String factoryId = factoryClass.getName();
-
         // Use the system property first
-        String className = fromSystemProperty(factoryId);
+        String className = fromSystemProperty(factoryClass.getName());
         if (className != null) {
             T result = newInstance(className, factoryClass, loader);
             if (result != null) {
@@ -72,7 +79,7 @@ private static <T> T find(Class<T> factoryClass, ClassLoader loader) throws Runt
 
         // handling Glassfish/OSGi (platform specific default)
 
-        T result = lookupUsingHk2ServiceLoader(factoryId, factoryClass, loader);
+        T result = lookupUsingHk2ServiceLoader(factoryClass, loader);
         if (result != null) {
             return result;
         }
@@ -80,16 +87,14 @@ private static <T> T find(Class<T> factoryClass, ClassLoader loader) throws Runt
         return null;
     }
 
-    @SuppressWarnings({"unchecked"})
     private static <T> T newInstance(String className, Class<T> factoryClass, ClassLoader classLoader) throws RuntimeException {
         checkPackageAccess(className);
         try {
-            Class<T> clazz;
-            if (classLoader == null) {
-                clazz = (Class<T>) Class.forName(className);
-            } else {
-                clazz = (Class<T>) Class.forName(className, false, classLoader);
+            Class<?> clazz;
+            if (classLoader == null) { //Match behavior of ServiceLoader
+                classLoader = ClassLoader.getSystemClassLoader();
             }
+            clazz = Class.forName(className, false, classLoader);
             return clazz.asSubclass(factoryClass).getConstructor().newInstance();
         } catch (ClassCastException wrongLoader) {
             return null;
@@ -102,41 +107,59 @@ private static String fromSystemProperty(String factoryId) {
         String systemProp = System.getProperty(factoryId);
         return systemProp;
     }
-
-    private static final String OSGI_SERVICE_LOADER_CLASS_NAME = "org.glassfish.hk2.osgiresourcelocator.ServiceLoader";
-
-    @SuppressWarnings({"unchecked"})
-    private static <T> T lookupUsingHk2ServiceLoader(String factoryId, Class<T> factoryClass, ClassLoader loader) {
-        Class<?> target;
-        try {
-            target = Class.forName(OSGI_SERVICE_LOADER_CLASS_NAME, false, loader);
-        } catch (ClassNotFoundException ignored) {
-            return null;
+    
+    private static Class<?>[] getHk2ServiceLoaderTargets(Class<?> factoryClass) {
+        ClassLoader[] loaders = new ClassLoader[]{
+                Thread.currentThread().getContextClassLoader(), 
+                    factoryClass.getClassLoader(), 
+                    ClassLoader.getSystemClassLoader()};
+        
+        Class<?>[] classes = new Class<?>[loaders.length];
+        int w = 0;
+        for (ClassLoader loader : loaders) {
+            if (loader != null) {
+                try {
+                    classes[w++] = Class.forName("org.glassfish.hk2.osgiresourcelocator.ServiceLoader", false, loader);
+                } catch (ClassNotFoundException | LinkageError ignored) {  
+                }
+            }
+        }
+        
+        if (classes.length != w) {
+           classes = Arrays.copyOf(classes, w);
         }
+        return classes;
+    }
 
-        try {
-            // Use reflection to avoid having any dependency on HK2 ServiceLoader class
-            Class<?> serviceClass = Class.forName(factoryId, false, loader);
-            Class<?>[] args = new Class<?>[]{serviceClass};
-            Method m = target.getMethod("lookupProviderInstances", Class.class);
-            Iterable<?> iterable = ((Iterable<?>) m.invoke(null, (Object[]) args));
-            if (iterable == null) {
-                return null;
+    @SuppressWarnings({"unchecked"})
+    private static <T> T lookupUsingHk2ServiceLoader(Class<T> factoryClass, ClassLoader loader) {
+        for (Class<?> target : getHk2ServiceLoaderTargets(factoryClass)) {
+            try {
+                // Use reflection to avoid having any dependency on HK2 ServiceLoader class
+                Class<?> serviceClass = Class.forName(factoryClass.getName(), false, loader);
+                Class<?>[] args = new Class<?>[]{serviceClass};
+                Method m = target.getMethod("lookupProviderInstances", Class.class);
+                Iterable<?> iterable = ((Iterable<?>) m.invoke(null, (Object[]) args));
+                if (iterable != null) {
+                    Iterator<?> iter = iterable.iterator();
+                    if (iter.hasNext()) {
+                        return factoryClass.cast(iter.next()); //Verify classloader.
+                    }
+                }
+            } catch (Exception ignored) {
+                // log and continue
             }
-            Iterator<?> iter = iterable.iterator();
-            return iter.hasNext() ? factoryClass.cast(iter.next()) : null;
-        } catch (Exception ignored) {
-            // log and continue
-            return null;
         }
+        return null;
     }
 
     private static <T> T factoryFromServiceLoader(Class<T> factory, ClassLoader loader) {
+        //ClassLoader of null is treated as system classloader
         try {
             ServiceLoader<T> sl = ServiceLoader.load(factory, loader);
             Iterator<T> iter = sl.iterator();
             if (iter.hasNext()) {
-                return factory.cast(iter.next());
+                return factory.cast(iter.next()); //Verify loader
             } else {
                 return null;
             }