diff --git a/smack-tcp/src/main/java/org/jivesoftware/smack/tcp/XMPPTCPConnection.java b/smack-tcp/src/main/java/org/jivesoftware/smack/tcp/XMPPTCPConnection.java
index c6bdf45f4..fac6ecdc6 100644
--- a/smack-tcp/src/main/java/org/jivesoftware/smack/tcp/XMPPTCPConnection.java
+++ b/smack-tcp/src/main/java/org/jivesoftware/smack/tcp/XMPPTCPConnection.java
@@ -397,10 +397,15 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
             // There was a previous connection with SM enabled but that was either not resumable or
             // failed to resume. Make sure that we (re-)send the unacknowledged stanzas.
             unacknowledgedStanzas.drainTo(previouslyUnackedStanzas);
+            // Reset unacknowledged stanzas to 'null' to signal that we never send 'enable' in this
+            // XMPP session (There maybe was an enabled in a previous XMPP session of this
+            // connection instance though). This is used in writePackets to decide if stanzas should
+            // be added to the unacknowledged stanzas queue, because they have to be added right
+            // after the 'enable' stream element has been sent.
+            unacknowledgedStanzas = null;
         }
         if (isSmAvailable() && useSm) {
             // Remove what is maybe left from previously stream managed sessions
-            unacknowledgedStanzas = new ArrayBlockingQueue<Stanza>(QUEUE_SIZE);
             serverHandledStanzasCount = 0;
             // XEP-198 3. Enabling Stream Management. If the server response to 'Enable' is 'Failed'
             // then this is a non recoverable error and we therefore throw an exception.
@@ -1330,11 +1335,17 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
                     if (element instanceof Stanza) {
                         packet = (Stanza) element;
                     }
+                    else if (element instanceof Enable) {
+                        // The client needs to add messages to the unacknowledged stanzas queue
+                        // right after it sent 'enabled'. Stanza will be added once
+                        // unacknowledgedStanzas is not null.
+                        unacknowledgedStanzas = new ArrayBlockingQueue<>(QUEUE_SIZE);
+                    }
                     // Check if the stream element should be put to the unacknowledgedStanza
                     // queue. Note that we can not do the put() in sendPacketInternal() and the
                     // packet order is not stable at this point (sendPacketInternal() can be
                     // called concurrently).
-                    if (isSmEnabled() && packet != null) {
+                    if (unacknowledgedStanzas != null && packet != null) {
                         // If the unacknowledgedStanza queue is nearly full, request an new ack
                         // from the server in order to drain it
                         if (unacknowledgedStanzas.size() == 0.8 * XMPPTCPConnection.QUEUE_SIZE) {