If it is an imap mail account then it will synchronise with server. It is like a virtual copy of what is on server. Emails are stored on server. You can uncheck : 'Check for new messages at start up' You can uncheck : 'check for new messages every x minutes' You can uncheck : 'allow immediate server notifications when new messages arrive' Some servers have a setup to be able to connect if there is new mail. But if you invoke a deliberate request to download all messages in all accounts by clicking on 'Get Messages' then that is precisely what happens. There is a drop down selection, so you can choose which account you want to download messages from. if you no longer want the account, make sure you have full copies of emails and then 'Copy' them into suitable folders in 'Local Folders' mail account to get to get copies off server. If you can read the copied emails in 'Local Folders' mail account then you have a good copy on computer. Then you can unsubscribe from seeing folders on server and remove the imap account.