Threading problem with subject threading
Here is a pretty intricate problem. Assume a folder contains messages
M1: Subject A
M2: Subject A
and subject threading has grouped M1 and M2 together.
If M2's parent (say P) with a different subject B gets inserted into the folder, VM's threading database becomes inconsistent. Essentially, both M1's thread and P's thread claim ownership of M2.
M2's thread-list is reset. However, M1's thread-subtree still contains M2. The subject node for "A" seems to retain M2 as well.