#466: implemented AutoCloseable so that the connection pools shut down when Spring wants to shut down the application. Note: this does NOT work with try..with resource in combination with async emails being sent. And using it with try..with resource when not async doesn't make sense, because why have a connection pool in that case.

Author: bbottema

modules/core-module/src/main/java/org/simplejavamail/api/mailer/Mailer.java

@@ -7,7 +7,6 @@
 import org.jetbrains.annotations.Nullable;
 import org.simplejavamail.MailException;
 import org.simplejavamail.api.email.Email;
-import org.simplejavamail.api.email.EmailWithDefaultsAndOverridesApplied;
 import org.simplejavamail.api.mailer.config.EmailGovernance;
 import org.simplejavamail.api.mailer.config.OperationalConfig;
 import org.simplejavamail.api.mailer.config.ProxyConfig;
@@ -34,7 +33,7 @@
  * @see MailerRegularBuilder
  * @see Email
  */
-public interface Mailer {
+public interface Mailer extends AutoCloseable {
 	/**
 	 * In case Simple Java Mail falls short somehow, you can get a hold of the internal {@link Session} instance to debug or tweak. Please let us know
 	 * why you are needing this on <a href="https://github.com/bbottema/simple-java-mail/issues">simple-java-mail/issues</a>.

modules/simple-java-mail/src/main/java/org/simplejavamail/mailer/internal/MailerImpl.java

@@ -26,6 +26,7 @@
 import java.util.List;
 import java.util.Properties;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -445,4 +446,16 @@ public OperationalConfig getOperationalConfig() {
 	public EmailGovernance getEmailGovernance() {
 		return emailGovernance;
 	}
+
+	/**
+	 * NOTE: this doesn't work with try-with resource if emails are sent asynchronously. This auto-close is only
+	 * meant for Spring integration, for when Spring wants to close the Mailer bean.
+	 *
+	 * @see <a href="https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/beans/factory/DisposableBean.html">Spring DisposableBean</a>
+	 * @see Mailer#close()
+	 */
+	@Override
+	public void close() throws ExecutionException, InterruptedException {
+		shutdownConnectionPool().get();
+	}
 }