diff --git a/spring-integration-test-support/src/main/java/org/springframework/integration/test/mail/TestMailServer.java b/spring-integration-test-support/src/main/java/org/springframework/integration/test/mail/TestMailServer.java
index 04efe5ac0f..0c3cc328fa 100644
--- a/spring-integration-test-support/src/main/java/org/springframework/integration/test/mail/TestMailServer.java
+++ b/spring-integration-test-support/src/main/java/org/springframework/integration/test/mail/TestMailServer.java
@@ -215,9 +215,9 @@ public class TestMailServer {
 
 	public static class ImapServer extends MailServer {
 
-		private boolean seen;
+		private volatile boolean seen;
 
-		private boolean idled;
+		private volatile boolean idled;
 
 		ImapServer(int port) throws IOException {
 			super(port);