User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8a4) Gecko/20040927 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8a4) Gecko/20040927 I had used broadband (wireless) to download onto my notebook computer an IMAP folder with 3,000 messages. I then deleted about 1,000. I reconnected from a different site using a dial-up modem. The help system does not tell me what to expect. What I see is that it downloads some headers quickly. Then the messages that had been deleted from my INBOX reappear, but with an empty letter icon on the left. Then the hourglass icon continues for about 20 minutes. At times, I see "Loading message", etc. at the bottom. At times I see nothing at the bottom. The "spinner" (the M/Dragon icon at the top right) shows onlyh the "M" as if there is no activity. Occasionally, I see the Trash folder getting more messages, and eventually, the empty letters for the deleted INBOX messages start to disappear again. Continuing, I may have clicked on INBOX, I don't remember. But then all of my valid messages in INBOX get the empty letter icon on the left, and I can't view them. I see "Loading message" at the bottom. Since this continued for a very long time. I clicked on the bottom right icon to go offline. The hourglass icon continued and the "Loading message" at the bottom continued even though I was offline. I'm guessing that when I went online, Mozilla spent the 20 minutes re-downloading the messages that I had deleted from my INBOX. Then Mozilla seemed to transfer those messages to my Trash folder. Finally, Mozilla then notified the IMAP server (and only then) that the given messages should indeed be deleted. I don't understand why Mozilla couldn't have deleted the given messages (about 1,000) based only on headers and no body. If it used headers only, it should be much less than 20 minutes -- even with a slow 56kbps modem. I'm guessing that the offline facility was optimized for broadband use. If so, at least the help facility should say something about limitations in using the offline facility with a slow connection. Of course, I may have misunderstood how the offline facility should be used. If so, I apologize for my misunderstanding. Perhaps these comments will help to make clearer the documentation. Reproducible: Always Steps to Reproduce: 1. Pick an IMAP folder with 3,000 messages or so. In my case, this was about 55 MB of mail. 2. Download using broadband, and then go offline. 3. Shut down computer (notebook). Then restart, delete 1,000 messages, and then go online again. Watch it sync. (After deletion, I had about 45 MB of mail.) Actual Results: The slow performance with little user feedback described above. Expected Results: It should have been much faster. If its operation of sync'ing is interrupted by going offline again, then it should reset its state (turn off the hourglass cursor, and remove the "Loading message" string at the bottom.