FreeBSD-11.2-p2, amavisd-new-2.11.0_3,1, p5-DBD-mysql-4.046 (also 4.037), mysql57-server-5.7.23_1
When using p5-DBD-mysql releases after 4.037, amavisd-new creates false positives and erroneously adds a "tagged_above=0" label to message headers.
This is due to a change in p5-DBD-mysql-4.038 and later releases so that p5-DBD-mysql "now returns mysql doubles as perl doubles and mysql floats as perl floats (and not as a string anymore)."
Due to this change in data types, the p5-DBD-mysql client obtains erroneous '0' results from queries. The MySQL client obtains the correct values.
This thread describes the problem in more detail and includes a link with configuration files and debug logs:
The changelog for p5-DBD-mysql describes the changes instituted with its 4.038 release:
Please let me know if you need further info.
I am experiencing the same problem but with all versions higher than 4.0.38. This is why I keep a patched private port for now.
This issue is still present in p5-DBD-mysql-4.050, released this week. Other amavisd users report seeing the same issue.