If pop account: pop account will only download whatever is in the Inbox. Logon to webmail account and move all messages you do not want to download into a different folder. If imap account: Try these methods: Try number one first as it means you can completely select a batch of emails, still have them on server, but not downloadable on new laptop. 1. Logon to webmail account and create a folder. Move emails you do not want to download into that folder you created. In Thunderbird, do not select to subscribe to see that folder, so if it shows up, then unsubscribe from seeing it. This means you can still subscribe to see that new folder on old laptop in order to access those emails. 2. In Thunderbird, there is a setting in 'Account Settings' > Synchronisation & Storage' 'Synchronise the most recent X Days' You would need to know what the oldest date is for the emails on server that you do want to download. Non-synchronized messages are still accessible within Thunderbird. The only difference is that rather than downloading the entire message, only the message "headers" are downloaded. (Message headers contain information like the sender, recipient(s), subject, etc - everything except the body of the message.) The message body is not downloaded until you click on the message in the message list (which means that if you are not online, you can't read the message).