If you are using amavisd-new with a SQL server (Docs are located in /usr/share/doc/amavisd-new) you will see error messages similar to this:
(!)WARN save_info_final: sql exec: err=1054, 42S22, \
DBD::mysql::st execute failed: Unknown column 'rseqnum' \
in 'field list' at (eval 135)