(In reply to Kai Engert (:KaiE:) from comment #0)
Offline IMAP folder synchronization isn't working for me on 102.
I had a folder with missing messages in offline mode. We suspected some folder corruption. I quit Thunderbird, identified the file in my profile folder below ImapMail by its folder name, and delete both primary and .msf files.
First of all, just to be clear, deleting .msf and mbox files to fix a busted folder is not typically suggested as the 1st step for end users. Instead, right-click->Properties->Repair Folder is the documented method. However, removing the .msf and mbox files is something I do a lot while debugging problems.
I started Thunderbird, and it re-synched the headers of the folder.
However, after having kept it running for 8 hours, overnight with no other activity, the folder still was NOT downloaded. (To confirm, I quit Thundebird again, and I only had a .msf file, no mail contents.)
Probably the first thing to check is make sure autosync is enabled. Possibly at some point
mail.server.default.autosync_offline_stores got set false. Without this true, individual messages are only downloaded and stored in the mbox file when they are opened.
Also, make sure there were no attempts to create account specific autosync settings with
mail.server.serverX.autosync_offline_stores where X is the server/account index/key number, 1, 2, 3 ....
Another thing is check to make sure
mail.imap.use_status_for_biff is true (the default). I think I saw somewhere that this is needed for autosync.
I did this several times on two accounts with successful results by following these steps:
- Shutdown TB
- Delete the <folder-name>.msf file for folder having offline store, e.g., INBOX.msf
- Delete the <folder-name> mbox file, e.g., INBOX
- Repeat the above 2 step for any other folder in the account you want to re-download that has offline store configured
- Start TB and select any folder in the same account
- Autosync requires TB be "idle" for 10 seconds before it starts, so don't do anything in TB for at least 10 seconds.
- First, all the headers for the removed files are downloaded and stored in re-created <folder-name>.msf files
- After header downloads finish each full message in <folder-name> having offline store is downloaded and stored in <folder-name> mbox files
If there are enough messages in the folders so that the download is not almost instantaneous, you should see the in the status bar at the bottom the activity for downloading the headers for all folders followed by slower progressing activity for downloading the full messages for all folders which are added to the <folder-name> mbox files.
However, I tried this again with a folder that is a subfolder of Inbox that has offline store. But on restart that folder didn't automatically download and create a new mbox file containing all the messages. I had to click the subfolder of Inbox before it downloaded and created the mbox file. I don't have to do this, it seems, with Inbox or other folders at the same level as Inbox.
Possibly the folder that didn't download for you was a subfolder? Also, did clicking on/opening the folder finally trigger the download and mbox creation?
Other that this, it appears that autosync is downloading and re-creating and populating the user-deleted .msf and mbox files properly.
I will look closer at the code for autosync and try to determine why lower level folders are not automatically autosync-ing and require that the folder be clicked (opened).