A couple of options: '''option POP:''' If you create a POP mail account, it will only look at and download from the server Inbox. So, you could logon to gmail webmail account and make sure that all old mail you do not want downloading is not in the Inbox. Move them to other folders. They will always be available in the webmail account, but you should keep an eye on how much quota you use. then whilst in webmail select the option to use Pop forwarding and not IMAP. then when you create the existing mail account in Thunderbird, make sure POP has been selected, as Thunderbird does default to IMAP. '''Option IMAP:''' After creating an IMAP mail account, check settings to make sure you are only synchronising the most recent emails: Tools > Account Settings > Synchronisation and storage or menu icon > Options > Account Settings > Synchronisation and storage select the option to only synchronise the most recent xx days. * https://support.mozilla.org/en-US/kb/imap-synchronization#w_configuring-synchronization-and-disk-space-usage * https://support.mozilla.org/en-US/kb/thunderbird-and-gmail Be selective with what folders you want to subscribe to see. Do not subscribe to see the gmail 'All Mail' folder, It stores all your emails and is gmails archive of all your emails.