+++ This bug was initially created as a clone of Bug #857436 +++ [Build ID] > Mozilla/5.0 (Windows NT 5.1; rv:22.0) Gecko/20100101 Thunderbird/22.0a1 > Application Build ID : 20130325031104 Empty Mbox/cur/nnnn directory is created by first mail copy from MaildirStore/IMAP/Offline-Use=On folder, if Mbox directory and Mbox/cur directory is not created yet. This problem was found during setups for test of bug 857003 and bug 857436. [Steps to reproduce] (1) Create Maildirstore/IMAP/Offline-Use=Off folder, call Mbox. => Mbox.msf is created. (2) Change Mbox to Offline-Use=On. => Mbox directory, Mbox\cur directory, Mbox\tmp directory, is not created yet. (3) Copy a mail to Mbox from MaildirStore/IMAP/Offline-Use=On folder => msgDBHdr is copied to Mbox.msf, and mail is shown at thread pane. (4) Click mail. => Mbox directory, Mbox\cur directory is created. => Empty Mbox/cur/nnnn is created. Once this "empty Mbox/cur/nnnn" is generated in MaildirStore/IMAP/Offline-Use=On folder, the "empty Mbox/cur/nnnn" is easily propagated to other MaildirStore/IMAP/Offline-Use=On folder and MaildirStore/LocalMbox by simple "Mail Copy", even by "step by step copy", "copy one mail per one copy operation". I believe that cause of this kind of problem is usually lack of "file/directory existence check", "file or directory check", "file size check" etc., and lack of "error return code/error status check" in many places of Tb's code. Patch by bug 674742 is a n example of sorting out work done in "Compact of BerkleyStore" to resolve data loss problem like bug 498814 and its dups.

I believe that the changes that I did to nsMsgMaildirStore::GetMsgInputStream in bug 1017939 addressed the cause of this. If not, feel free to reopen.