Opera Mail - Incomplete export
I tried to store my mails with Mailstore but the mbs file generated by Opera seems incomplete - I cannot see last month mails and some more (impossible to check all missing emails). Same thing if I try to import them in Thunderbird. Did I miss something ?
Is this with IMAP or POP? Make sure you don't have low-bandwidth mode on if you're using POP. For IMAP, make sure you don't have low-bandwidth mode on and make sure you don't have "do not download attachments" turned on and make sure you have "make all messages available offline" set. Otherwise, all messages won't exist in full in Opera's mail store.
I mention that as all messages are already stored as mbs files in Opera's mail/store folder ("drafts" for all accounts and an accountN folder for each account). So, there's no need to export unless you want to group all messages for a view into a single mbs file.
But, since you're exporting, Opera should ask you if you want to fetch incomplete messages. After you tell it yes, you have to do the export again (othewise Opera will do nothing).
What views did you export? When exporting a view in the mail panel, what messages are exported depends on the "settings for this view" "show" settings (the button is on the toolbar above the message list. Also, if you've enabled the period button (a per-view setting to hide messages older than a certain date), make sure each view is set to "forever".
You also might want to make sure the main database and indexer database are not corrupted. You can run a test that will fix some minor corruption. But, if something is really messed up, you can't rely on exporting via the UI and instead need to import from the mail/store folder.
If this is with POP and you can't see last months mails no matter what, you can close down Opera and delete the uid file for the pop account. It's numbered based on the accounts listed in accounts.ini and is in the pop3 folder in the mail folder. That'll cause Opera to refetch all messages thar are on the server in the Inbox (causing duplicates if they're showing in Opera already).
If this is with IMAP, you can unsubscribe from a folder and resubscribe. But, don't do this unless you're using the Opera Mail standalone version or Opera 12.14+ as it'll wipe out messages in the IMAP folder due to a bug.
(On a side, for my sake, for future reference, please prefix Opera Mail thread subjects with "Opera Mail - " so I don't miss them.)