It is a custom domain name email, not gmail. I was using it with IMAP. I’ve asked my hosting provider if they are able to somehow restore the emails.

No the inbox file is not in the chest I’m afraid, that’s why it’s so frightening. If avast can do this to you just because of an email containing false positive than avast has serious issues.

Unfortunately I don’t have a backup because I was using live sync with IMAP. When my offline emails got deleted in Mozilla Thunderbird it synced with the email server and deleted the emails there as well. A tragedy.