I recently installed Thunderbird on a new computer, and copied the relevant directories than contained all the messages/account information from my old PC's Thunderbird installation to my new one. I did have to re-enter the account passwords, but after that all seemed to be working OK. I have now noticed that some of the automatic message filtering that I had previously set up doesn't work and that the messages are left in the inbox. If I 'Run filters on folder' then the filters work, and the messages are moved to the correct folders accordingly. FYI, I have 10 Mail accounts, all using POP. One of the accounts has its own dedicated inbox, all the others use the local folders inbox. (This dedicated inbox accounts filters only seem to work manually). Of the remaining 9 accounts, one is filtered by it's account name, the other 8 are filtered via the Local Folders filter. I have 294 filters in total. All filters have the 'Manually Run' and 'Getting New Mail' tick box's checked and 'Filter before Junk Classification'. I would have linked my problem with the Forum Question 'If I apply mail filters for message body , the filters stop applying automatically', however my problem appears to be random, and doesn't just apply to message body filters. Has this problem been caused by the transfer of the accounts from one computer to another, or has this transfer just shown up a bug? Am I likely to have to Identify which of the filters aren't working and have to re-enter them? (With 294 filters with a potential problem, this would take ages!). And would this cure the problem?