Yes —
that can work, but there is one important catch:
Important catch
If you restore
Inbox.OLD back to
Inbox, the
old detections may reappear immediately, because you are putting the old mailbox content back where Thunderbird reads it.
That does
not mean a new infection — only that the old stored message content is visible again.
Short answer
Yes, you can rename
Inbox.OLD back to
Inbox,
but only with Thunderbird closed.
Safe way to do it
- Close Thunderbird completely.
- In the mailbox folder, rename the current empty
Inbox to something like:
- Rename
Inbox.OLD back to:
- Do the same for the index file if needed:
Inbox.msf.OLD back to Inbox.msf
- Open Thunderbird.
Your “delete older messages bit by bit” idea
Yes — that is a
reasonable way to isolate the problem, especially since Thunderbird makes bulk deletion by date easy.
But there is a second important catch
You just said you copied the whole old Andorra inbox into another Thunderbird account:
That means the same suspicious message may exist in
two places:
- the old Andorra Inbox
- the copied AndorraIN folder in the Gmail account
So if you clean one copy but
not the other, ESET may still find it.
Best practical plan
1. Back up first
Copy both of these to external storage before changing anything:
- the old Andorra mailbox
- the Gmail
AndorraIN copy
2. Restore only one mailbox for testing
Restore the Andorra
Inbox.OLD back to
Inbox as above.
3. Delete by date in Thunderbird
Since the mailbox only goes back to
2016, you can prune in chunks.
I would suggest:
- Delete the oldest large block first
- Empty Trash
- Run File > Compact Folders
- Close Thunderbird
- Run ESET
- See whether the detection remains
4. If detection remains
Repeat with the next block.
Better than “bit by bit”
To save time, do it in
large date ranges, for example:
- delete 2016–2018
- scan
- if still detected, restore from backup if needed and try another range
- or continue with 2019–2020
Very important
Because the old Andorra mail was copied to
AndorraIN, you may need to do the
same cleanup there too.
Otherwise:
- detection disappears from old Andorra Inbox
- but remains in
AndorraIN
My recommendation
If your goal is to
identify the bad message while keeping most old mail:
- Back up both copies
- Restore
Inbox.OLD to Inbox
- Delete old mail by date ranges, not one by one
- Compact folders
- Scan
- If needed, repeat
- Then remember to check
AndorraIN too
Final note
If you want, when you come back this afternoon, I can help you design the
best date-range test order so you can narrow it down with the fewest scans.