User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; nl; rv:22.214.171.124) Gecko/20091201 Firefox/3.5.6 Build Identifier: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; nl; rv:126.96.36.199) Gecko/20091204 Lightning/1.0b1 Thunderbird/3.0 After a timezone change (tested for direction east to west, e.g. Europe to America; not sure if same would happen in opposite direction) Thunderbird starts redownloading all Imap folders. Reproducible: Always Steps to Reproduce: Steps to be carried out while online. 1. Have all Imap folders downloaded and close TB 2. Change time zone setting to a time zone west 3. Reopen TB Not entirely sure about reproducibility as TB 3 has no clear indication as of whether everything's downloaded (i.e. whether step 1 is completed). Actual Results: TB starts redownloading all Imap folders. Expected Results: TB should use the existing offline folders. In TB 2 the whole IMAP folders would disappear from the user interface when offline during step 3. That behaviour I could not reproduce in TB 3. I've reported these results (for TB2) earlier in https://bugzilla.mozilla.org/show_bug.cgi?id=394061 but I failed to correctly identify the trigger (i.e. the timezone change) at that time.