My emails from the last five years have disappeared and trying to receive new emails generates an error message

Question

My antivirus scan secured a FakeAlert threat. Now, all emails from the past five years are no longer visible in my Inbox and are not in the Deleted Items folder. Any time I try to receive a new email I receive the following message:
"There was an error downloading the following message:
From: <sender>
Subject: <subject>
This message may contain a virus or there is not enough disk space. Skip this message?"
Enter No:
"Unable to write the email to the mailbox. Make sure the file system allows you write privileges, and you have enough disk space to copy the mailbox."
I have write privileges and 184 GB of free disk space. I recently deleted many emails and compacted my inbox. I cannot restore any files that the scan deleted because there are none visible.
I have contacted my antivirus software providers and they concluded that the problem lies with my email software. Can you please help?

Answer 1

REmove all emails from the Inbox to other folders.
When it is empty do the next stage.
If you are using a POP mail account and have some emails in the webmail view that are missing in Thunderbird, you could get everything currently on the server downloaded again.
Make hidden files and folders visible:
* http://kb.mozillazine.org/Show_hidden_files_and_folders
In Thunderbird
* Help > Troubleshooting Information
* click on 'Show Folder' button
* '''close Thunderbird now - this is important. '''
* clickon 'Mail' folder
* click on mail account name
* Locate and delete these files: '''Inbox and Inbox.msf'''
* locate and delete this file: '''popstate.dat'''
* close the window - top right X
* restart Thunderbird
A new Inbox will be created.
A new popstate.dat file will be created.
It keeps a record of everything downloaded, as it is new and empty, TB will believe everything currently in server Inbox needs to be downloaded.
This will get everything currently in server Inbox back in Thunderbird. As you already have some emails, you may get some duplicates, but only the once.
I would not expect any emails are recoverable from the Inbox in Thunderbird because they may have been corrupted by either an unknown reason or by the antivirus program doing something with the file to make emails lose information, it is possible that when you compacted the file emails were lost. Compacting removes 'marked as deleted' emails, but if it didi not know where a marked as deleted email ended, good emails could have been removed due to the corruption.
In future, compacting should be done on a regular basis, but never compact a file/folder that you think may be corrupted. Getting the error message saying the file may be corrupted was a good hint that somethig was wrong.
Report back on results.