diff --git a/applications/source/mail-source/pom.xml b/applications/source/mail-source/pom.xml
index 3cd70a18..bfd6c5e1 100644
--- a/applications/source/mail-source/pom.xml
+++ b/applications/source/mail-source/pom.xml
@@ -32,9 +32,11 @@
             <exclusions>
                 <exclusion>
                     <groupId>com.sun.mail</groupId>
+                    <artifactId>jakarta.mail</artifactId>
                 </exclusion>
                 <exclusion>
                     <groupId>jakarta.activation</groupId>
+                    <artifactId>jakarta.activation-api</artifactId>
                 </exclusion>
             </exclusions>
         </dependency>
diff --git a/functions/function/filter-function/src/main/java/org/springframework/cloud/fn/filter/FilterFunctionConfiguration.java b/functions/function/filter-function/src/main/java/org/springframework/cloud/fn/filter/FilterFunctionConfiguration.java
index 89179722..cef6f671 100644
--- a/functions/function/filter-function/src/main/java/org/springframework/cloud/fn/filter/FilterFunctionConfiguration.java
+++ b/functions/function/filter-function/src/main/java/org/springframework/cloud/fn/filter/FilterFunctionConfiguration.java
@@ -18,8 +18,6 @@ package org.springframework.cloud.fn.filter;
 
 import java.util.function.Function;
 
-import reactor.core.publisher.Flux;
-
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
@@ -35,17 +33,22 @@ import org.springframework.messaging.Message;
 public class FilterFunctionConfiguration {
 
 	@Bean
-	public Function<Flux<Message<?>>, Flux<Message<?>>> filterFunction(
-			ExpressionEvaluatingTransformer filterExpressionEvaluatingTransformer) {
+	public Function<Message<?>, Message<?>> filterFunction(
+		ExpressionEvaluatingTransformer filterExpressionEvaluatingTransformer) {
 
-		return flux ->
-				flux.filter((message) ->
-						(Boolean) filterExpressionEvaluatingTransformer.transform(message).getPayload());
+		return message -> {
+			if ((Boolean) filterExpressionEvaluatingTransformer.transform(message).getPayload()) {
+				return message;
+			}
+			else {
+				return null;
+			}
+		};
 	}
 
 	@Bean
 	public ExpressionEvaluatingTransformer filterExpressionEvaluatingTransformer(
-			FilterFunctionProperties filterFunctionProperties) {
+		FilterFunctionProperties filterFunctionProperties) {
 
 		return new ExpressionEvaluatingTransformer(filterFunctionProperties.getExpression());
 	}
diff --git a/functions/function/filter-function/src/test/java/org/springframework/cloud/fn/filter/FilterFunctionApplicationTests.java b/functions/function/filter-function/src/test/java/org/springframework/cloud/fn/filter/FilterFunctionApplicationTests.java
index 163c3ca4..6cf98aa6 100644
--- a/functions/function/filter-function/src/test/java/org/springframework/cloud/fn/filter/FilterFunctionApplicationTests.java
+++ b/functions/function/filter-function/src/test/java/org/springframework/cloud/fn/filter/FilterFunctionApplicationTests.java
@@ -16,11 +16,15 @@
 
 package org.springframework.cloud.fn.filter;
 
+import java.util.List;
 import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
 
 import org.junit.jupiter.api.Test;
-import reactor.core.publisher.Flux;
-import reactor.test.StepVerifier;
+
+
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Qualifier;
@@ -30,6 +34,8 @@ import org.springframework.messaging.Message;
 import org.springframework.messaging.support.GenericMessage;
 import org.springframework.test.annotation.DirtiesContext;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 /**
  * @author Artem Bilan
  * @author David Turanski
@@ -40,21 +46,17 @@ public class FilterFunctionApplicationTests {
 
 	@Autowired
 	@Qualifier("filterFunction")
-	Function<Flux<Message<?>>, Flux<Message<?>>> filter;
+	Function<Message<?>, Message<?>> filter;
 
 	@Test
 	public void testFilter() {
-		Flux<Message<?>> messageFlux =
-				Flux.just("hello", "hello world")
-						.map(GenericMessage::new);
-		Flux<Message<?>> result = this.filter.apply(messageFlux);
-		result
-				.map(Message::getPayload)
-				.cast(String.class)
-				.as(StepVerifier::create)
-				.expectNext("hello world")
-				.expectComplete()
-				.verify();
+		Stream<Message<?>> messages = List.of("hello", "hello world")
+			.stream()
+			.map(GenericMessage::new);
+		List<Message<?>> result = messages.filter(message -> this.filter.apply(message) != null).collect(Collectors.toList());
+		assertThat(result.size()).isEqualTo(1);
+		assertThat(result.get(0).getPayload()).isNotNull();
+		assertThat(result.get(0).getPayload()).isEqualTo("hello world");
 	}
 
 	@SpringBootApplication
diff --git a/functions/function/http-request-function/README.adoc b/functions/function/http-request-function/README.adoc
index d0a0ad41..e3f4bf01 100644
--- a/functions/function/http-request-function/README.adoc
+++ b/functions/function/http-request-function/README.adoc
@@ -2,7 +2,7 @@
 
 This module provides an HTTP request function that can be reused and composed in other applications.
 The `Function` uses the reactive `WebClient` from `Spring WebFlux` and is implemented as a `java.util.function.Function`.
-This function gives you a reactive stream of `ResponseEntity` given a stream of request messages as the function a signature of `Function<Flux<Message<?>,Flux<ResponseEntity>>`.
+This function gives you a reactive stream of `ResponseEntity` given a stream of request messages as the function a signature of `Function<Message<?>,ResponseEntity>`.
 Users have to subscribe to the returned `Flux` to receive the data.
 
 ## Beans for injection