title: Proper logging configuration to disable django error emails
body: <p>I just got sentry working in my environment and I tried tweaking my logging to make it stop sending error emails, but it still is and I don't understand why. My logging config is:</p>
  
  <pre><code>LOGGING = {
      "version": 1,
      "disable_existing_loggers": False,
      "formatters": {
          "verbose": {
              "format": '%(levelname)s %(asctime)s (%(pathname)s %(funcName)s): "%(message)s"'
          },
          "simple": {"format": "%(levelname)s %(message)s"},
          "django.server": {
              "()": "django.utils.log.ServerFormatter",
              "format": "[%(server_time)s] %(message)s",
          },
      },
      "handlers": {
          "null": {"level": "DEBUG", "class": "logging.NullHandler",},
          "console": {
              "level": "DEBUG",
              "class": "logging.StreamHandler",
              "formatter": "simple",
          },
          "log_file": {
              "level": "DEBUG",
              "class": "logging.handlers.RotatingFileHandler",
              "filename": "/var/log/courtlistener/django.log",
              "maxBytes": "16777216",  # 16 megabytes
              "formatter": "verbose",
          },
          "django.server": {
              "level": "INFO",
              "class": "logging.StreamHandler",
              "formatter": "django.server",
          },
      },
      "loggers": {
          # Disable SuspiciousOperation.DisallowedHost exception ("Invalid
          # HTTP_HOST" header messages.) This appears to be caused by clients that
          # don't support SNI, and which are browsing to other domains on the
          # server. The most relevant bad client is the googlebot.
          "django.security.DisallowedHost": {
              "handlers": ["null"],
              "propagate": False,
          },
          "django.server": {
              "handlers": ["django.server"],
              "level": "INFO",
              "propagate": False,
          },
          # This is the one that's used practically everywhere in the code.
          "cl": {"handlers": ["log_file"], "level": "INFO", "propagate": True,},
      },
  }
  </code></pre>
  
  <p>Is there a missing piece here? I don't know how that'd possibly send emails. Is there another config variable I should be thinking about?</p>
  
  <p><strong>UPDATE</strong>: One thing I've noticed is that I get <em>plaintext</em> error emails now instead of the HTML ones I used to get. This changed when I tweaked the logging config, but I have no idea why and Googling it doesn't seem to reveal anything. </p>