If you have http.cfg:http_log_level=6, then there will be log messages lke
# delete-to-Trash
exmdb-audit: moved(mmv) message /var/lib/gromox/user/horio:f15:m589825 to f11:m458752
# recoverable delete (= set "hidden" attribute)
exmdb-audit: soft-deleted message /var/lib/gromox/user/horio:f13:m196615 (actor:owner)
# recovering a deleted item is implemented by copying off the hidden message to a new one and then discarding the hidden one
exmdb-audit: copied(mmv) message /var/lib/gromox/user/horio:f13:m196615 to f13:m196616
exmdb-audit: hard-deleted message /var/lib/gromox/user/horio:f13:m196615 (actor:owner)
So you can see which actions OL triggered.