This use case is not really supported because I've never tried it.
The amavis-logwatch utility is an amavisd-new log parser, that
produces summaries, details, and statistics regarding the operation of
-amavisd-new. It can be used as a standalone program to produce summary
-and detailed reports from within logwatch.
+amavisd-new.
A key feature of amavis-logwatch is its ability to produce a very wide
range of reports with data grouped and sorted as much as possible to