This allows collection of attachment count and size statistics. This involves processing the MIME of every email so can be a little slower.
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RouteStats
This allows collection of time-based statistics for every email route detected. This will increase the RAM and disk usage of the statistics collected and will be a little slower.
For each route stats are collected for the quarterly, weekly and daily count, size, attachment count and attachment sizes. This can be up to 0.5GB for 200,000 routes.