B4J Question Crashing on smtp sending

This is becoming a major problem for my project. We mass mail a large number of addresses after awhile it errors out and crashes. The invalid address errors are for genuine bad addresses but I don't know why it eventually crashes entirely.

An example from the log.
java.lang.RuntimeException: Empty writer returned: 554 5.5.1 Error: no valid recipients
at anywheresoftware.b4a.net.SMTPWrapper$1.run(SMTPWrapper.java:313)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
java.lang.RuntimeException: Empty writer returned: 554 5.5.1 Error: no valid recipients
java.lang.RuntimeException: Empty writer returned: 554 5.5.1 Error: no valid recipients
java.lang.RuntimeException: java.net.SocketException: Socket closed
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:120)
at anywheresoftware.b4a.shell.ShellBA.raiseEvent2(ShellBA.java:98)
at anywheresoftware.b4a.BA$3.run(BA.java:247)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:428)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.net.SocketException: Socket closed
at java.base/java.net.SocketInputStream.socketRead0(Native Method)
at java.base/java.net.SocketInputStream.socketRead(SocketInputStream.java:115)
at java.base/java.net.SocketInputStream.read(SocketInputStream.java:168)
at java.base/java.net.SocketInputStream.read(SocketInputStream.java:140)
at java.base/java.io.BufferedInputStream.fill(BufferedInputStream.java:252)
at java.base/java.io.BufferedInputStream.read(BufferedInputStream.java:271)
at java.base/java.io.DataInputStream.readByte(DataInputStream.java:270)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:229)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:167)
at jdk.internal.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:91)
... 9 more
java.lang.NullPointerException