I have been using Thunderbird for years in the following manner (now it's Thunderbird 17.0 on Windows 7):
I offload my IMAP emails to my local inbox weekly, then apply hundreds of message filters to said emails in order to move and store them into a few hundred subfolders. It's always worked like a charm - until recently.
Now, after I apply the message filters, the emails get moved but they are destroyed in the process - bodies are scrambled up, with bits and pieces of other emails or they are simply blank!
How do I fix this?