Comment 157 for bug 275471

More info:

I set up an entirely empty IMAP account in thunderbird and moved the 1MB and 6MB files to it. I set this up for offline mode and ran the 'Download Now' to force the offline sync.

THIS WORKED!

The 6MB file is now loaded instantly and available when offline. I can save the attachment to my local disk and it doesn't download off the server.

So we can break down the problem into:

1. Normal cache not working - consensus is this seems to be broken generally (separate bug?)

2. Offline files sync broken for large mailboxes - seems to work on small mailboxes. Doing a 'sync now' on a large mailbox (100,000 emails, 100 folders, selected for offline use 10 folders, 10,000 emails) doesn't seem to actually work - perhaps some timeout in effect?

3. Cache -> Offline files - why on earth does TB not put out to offline files as it downloads email? Why is Offline files sync a separate process? Surely it makes sense to update the offline files storage from Cache so there is still a single download.

Are there open bugs for the above already? If not, and if people can replicate, we should open them. I get the feeling putting all this effort into a 'RESOLVED INVALID' bug may be falling of deaf ears.