diff --git a/aprsd/packets/core.py b/aprsd/packets/core.py
index 8a2ddcd..351c9c5 100644
--- a/aprsd/packets/core.py
+++ b/aprsd/packets/core.py
@@ -18,6 +18,7 @@ LOG = logging.getLogger("APRSD")
 
 PACKET_TYPE_MESSAGE = "message"
 PACKET_TYPE_ACK = "ack"
+PACKET_TYPE_REJECT = "reject"
 PACKET_TYPE_MICE = "mic-e"
 PACKET_TYPE_WX = "weather"
 PACKET_TYPE_OBJECT = "object"
@@ -209,6 +210,23 @@ class AckPacket(PathPacket):
         )
 
 
+@dataclass
+class RejectPacket(PathPacket):
+    response: str = None
+
+    def __post__init__(self):
+        if self.response:
+            LOG.warning("Response set!")
+
+    def _build_raw(self):
+        """Build the self.raw which is what is sent over the air."""
+        self.raw = "{}>APZ100::{} :rej{}".format(
+            self.from_call,
+            self.to_call.ljust(9),
+            self.msgNo,
+        )
+
+
 @dataclass
 class MessagePacket(PathPacket):
     message_text: str = None
@@ -469,6 +487,7 @@ TYPE_LOOKUP = {
     PACKET_TYPE_WX: WeatherPacket,
     PACKET_TYPE_MESSAGE: MessagePacket,
     PACKET_TYPE_ACK: AckPacket,
+    PACKET_TYPE_REJECT: RejectPacket,
     PACKET_TYPE_MICE: MicEPacket,
     PACKET_TYPE_OBJECT: ObjectPacket,
     PACKET_TYPE_STATUS: StatusPacket,
@@ -485,6 +504,8 @@ def get_packet_type(packet: dict):
     packet_type = "unknown"
     if pkt_format == "message" and msg_response == "ack":
         packet_type = PACKET_TYPE_ACK
+    elif pkt_format == "message" and msg_response == "rej":
+        packet_type = PACKET_TYPE_REJECT
     elif pkt_format == "message":
         packet_type = PACKET_TYPE_MESSAGE
     elif pkt_format == "mic-e":
diff --git a/aprsd/threads/rx.py b/aprsd/threads/rx.py
index 3689040..f6cc35e 100644
--- a/aprsd/threads/rx.py
+++ b/aprsd/threads/rx.py
@@ -87,11 +87,18 @@ class APRSDProcessPacketThread(APRSDThread):
         self._loop_cnt = 1
 
     def process_ack_packet(self, packet):
+        """We got an ack for a message, no need to resend it."""
         ack_num = packet.msgNo
         LOG.info(f"Got ack for message {ack_num}")
         pkt_tracker = packets.PacketTrack()
         pkt_tracker.remove(ack_num)
-        return
+
+    def process_reject_packet(self, packet):
+        """We got a reject message for a packet.  Stop sending the message."""
+        ack_num = packet.msgNo
+        LOG.info(f"Got REJECT for message {ack_num}")
+        pkt_tracker = packets.PacketTrack()
+        pkt_tracker.remove(ack_num)
 
     def loop(self):
         try:
@@ -124,6 +131,11 @@ class APRSDProcessPacketThread(APRSDThread):
             and packet.addresse.lower() == our_call
         ):
             self.process_ack_packet(packet)
+        elif (
+            isinstance(packet, packets.RejectPacket)
+            and packet.addresse.lower() == our_call
+        ):
+            self.process_reject_packet(packet)
         else:
             # Only ack messages that were sent directly to us
             if isinstance(packet, packets.MessagePacket):