Simple server application in Python

Problem: My server application only accepts one connection at a time. I'd like to know why serverSocket.listen() doesn't listen and serverSocket.accept() doesn't accept all connections.

import socket

SERVER_ADDRESSES = ['0.0.0.0']
SERVER_PORT = 8091

CONNECTED_CLIENTS = {}


def processClientConnection(clientSocket, clientAddress):
    while True:
        try:
            print("Listening for messages...")
            message = clientSocket.recv(1024)
            message = message.decode("UTF-8")
            for client in CONNECTED_CLIENTS.keys():
                print(f"{CONNECTED_CLIENTS[client]} vs {clientAddress}")
                print(CONNECTED_CLIENTS[client] == clientAddress)
                if CONNECTED_CLIENTS[client] != clientAddress:
                    print(f"Sending message to {CONNECTED_CLIENTS[client]}")
                    client.send(b"%s: %s" % (CONNECTED_CLIENTS[client][0], message))
        except ConnectionResetError:
            print(f"{CONNECTED_CLIENTS[clientSocket][0]} disconnected!")
            for client in CONNECTED_CLIENTS.keys():
                if clientSocket != client:
                    client.send(b"%s disconnected!" % CONNECTED_CLIENTS[clientSocket][0])
            del(CONNECTED_CLIENTS[clientSocket])


def startServer(serverAddress):
    serverSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    print(f"Socket Host Name: {serverAddress}:{SERVER_PORT}")
    serverSocket.bind((serverAddress, 8091))
    # become a server socket
    while True:
        print("Listening for connections")
        serverSocket.listen()
        (clientSocket, address) = serverSocket.accept()
        if (clientSocket, address) in CONNECTED_CLIENTS:
            print("Can't connect multiple of same client")
            break
        CONNECTED_CLIENTS[clientSocket] = address
        print(f"{CONNECTED_CLIENTS[clientSocket][0]} connected!")
        ct = threading.Thread(target=processClientConnection, args=([clientSocket, address]))
        ct.run()


def runServer():
    for serverAddress in SERVER_ADDRESSES:
        serverThread = threading.Thread(target=startServer, args=([serverAddress]))
        serverThread.start()


if __name__ == '__main__':
    print('Server Started')
    runServer()

import socket

SERVER_ADDRESS = '127.0.0.1'
SERVER_PORT = 8091


def receiveMessage(sock):
    while True:
        try:
            message = sock.recv(1024).decode("UTF-8")
            if len(message):
                print(message)
        except ConnectionResetError:
            print("Server disconnected you")
            sock.close()
            exit(0)
        except ConnectionAbortedError:
            print("Server disconnected you")
            sock.close()
            exit(0)


def sendMessage(sock):
    while True:
        try:
            message = input()
            sock.send(bytes(message, "UTF-8"))
        except ConnectionResetError:
            print("Server disconnected you")
            sock.close()
            exit(0)
        except ConnectionAbortedError:
            print("Server disconnected you")
            sock.close()
            exit(0)
        except EOFError:
            print("Client closed")
            sock.close()
            exit(0)


def runClient():
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    try:
        s.connect((SERVER_ADDRESS, SERVER_PORT))
    except TimeoutError:
        print("Server down")
        s.close()
        exit(0)
    except ConnectionRefusedError:
        print("Server down")
        s.close()
        exit(0)

    print("Connected to server. Type your message.\n")

    messagingThread = threading.Thread(target=sendMessage, args=([s]))
    messagingThread.start()

    receivingThread = threading.Thread(target=receiveMessage, args=([s]))
    receivingThread.start()


if __name__ == '__main__':
    print("Client started")
    runClient()