Let's see if that will log it.

I'm not really sure.

docs/courier-to-mailman3.md

@@ -33,3 +33,4 @@ This is our current version trying to communicate between courier and mailman3.
   * Maybe this is better?  
   * Catch exception, log based on that?
   * Hm, go with bare "Exception"...  The catch wasn't what was failing.
+  * Let's try that instead?

source/courier-to-mailman3.py

@@ -67,6 +67,6 @@ try:
             raise
 except Exception as e:
     logger.error('lmtp error')
-    logger.error(traceback.format_exc())
+    logger.exception('Got exception Traceback:')
     logger.error('lmtp failed errorno: %s, message: %s', e.errno, e.strerror)
     exit(100)