I'm tracing out some issue with maildir, and it looks likes when messages are copied, their offline flag is set from the msgHdr but they are not actually offline. Eventually when you try to get the message, the initialization of the message stream fails, but the offline flag is never reset.

So this code looks off in nsIImapMailFolder.cpp: 8361 fakeHdr->SetMessageOffset(curOfflineStorePos); 8362 char storeToken[100]; 8363 PR_snprintf(storeToken, sizeof(storeToken), "%lld", curOfflineStorePos); 8364 fakeHdr->SetStringProperty("storeToken", storeToken); 8365 fakeHdr->OrFlags(nsMsgMessageFlags::Offline | nsMsgMessageFlags::Read, &resultFlags); Near the end of a message copy, we are setting the storeToken to an offset (while it should be a file name in the maildir case), then flagging the message as offline before the maildir store has successfully stored it (which will fail).

This is closely related to the failure we are seeing in the maildir version of test_offlineCopy.js and could be the main problem there.

Bug 1113275 fixes test_offlineCopy.js