I have a mail message that is corrupted in Thunderbird, but correct on the IMAP server (which is Gmail). Is it possible for me to tell Thunderbird to discard its copy and re-download it from the server?
Another option is to download the original message from Gmail, open it in Thunderbird, and then copy the message within Thunderbird back in to the original folder.
- Go to the menu for the message in Gmail (three dots in the top right) and select "show original"
- Select "download original"
- Select "Open with Thunderbird"
- Message -> copy to -> find your account and then the folder you would like the message added to.