If you are talking about a gmail imap account: Gmail keeps all your mail, incoming, outgoing and archived in the 'All Mail' folder. So they should be in the 'All Mail' folder. If emails did not show in the 'All Mail' folder, then they would not exist. You see emails in other folders, because gmail applies 'labels' which act like a filter tag, so allowing you to see emails in a more conventional view eg: Inbox, Sent, Drafts, Trash etc. Emails that are deleted must be put into the subscribed server gmail trash folder. When gmail auto removes that trashed email after 30 days, all labels are removed and email is also deleted from the 'All Mail' folder. If email is deleted but not put into the subscribed gmail server trash folder, then only the label is removed eg: Inbox, so email disappears from Inbox but it has been auto archived by gmail and is still in the 'All Mail' folder. What you need to determine is this. Is the 'Inbox' label not being applied in the first place? Is the label being applied but another account is using pop to download before the imap account is accessed? Is the label being applied but Anti-Virus product scanned and auto fixed an mbox file, thus deleting emails from Inbox? Logon to gmail webmail account via a browser before opening Thunderbird or any other device eg: Phone. Are new emails in the 'Inbox' ? If yes, then you know gmail is correctly applying the Inbox label. '''Q:''' Are new emails shown in the webmail view of Inbox? Now start Thunderbird. '''Q:''' Do emails get downloaded to Thunderbird gmail Inbox ? What Anti-Virus product do you use ? The following is a possible explanation of what might have occured. It is possible that the AV product is scanning Thunderbird files on startup and at some point did not like something. If the AV is set to auto fix files, then it could have deleted the entire Inbox mbox file full of various emails. This would have then left you with a clean empty Inbox which connects to server and removes emails from server Inbox as seen via webmail. As those deleted emails did not get put into the gmail subscribed trash folder, they only had the 'Inbox' label removed and so now only appear in the server 'All Mail' folder. You can reapply Inbox labels to those emails to get them to appear in the Inbox. Another possibility: You used a phone/another device to see emails, but the phone/another device used a pop protocol without account settings to 'leave message on server', so emails were popped off the server. This means nothing is in the server Inbox, so nothing can be seen in imap account Inbox, but as no pop account has access to server trash, emails do not get deleted, they are archived in 'All Mail'.