You seem to not understand what an email client does. When you create a POP or IMAP mail account in Thunderbird, it's purpose is to offer access to email that are received by the server for a particular email address. POP means it can only access the server Inbox and download anything not previously downloaded to the mail account Inbox in Thunderbird. These emails are stored in your profile folder and you can access them even when in offline mode. You can control settings to either download and delete copy off server, or leave a copy on server and there are further options on when to delete off server. IMAP is a remote view of the server folders. You subscribe to see folders and their contents. Email headers are downloaded and when you select to read an email , it is retrieved from the server and stored in a temporary cache. These emails are not stored in Thunderbird, they are stored on server and you will not get access if in offline mode. If you synchronise subscribed folders then a copy of the folder on the server is downloaded and stored in your Profile folder and you can access those emails in offline mode. If you delete in Thunderbird, it will delete off the server. The folders continue to synchronise so that Thunderbird folders are the same as the ones on the server. The folders are really one and the same. So, in your case, if you stop the account with Hotmail, then you will not have any access to server via webmail and neither will Thunderbird. If the account does not exist, then the email address will not exist and any emails on server in that account will be deleted. What does this mean regarding emails? If POP then make sure you 'Get Messages' downloaded before the account expires. Then you will lose everything on server, but you should have all your emails still stored in your Thunderbird profile folder. The pop mail account does not have to deleted you just need to stop it from accessing the server to check for emails OR you can move all your emails into suitable folders in the 'Local Folders' account and then remove the pop mail account. If IMAP, make sure you synchronise all your subscribed folders to get a copy into Thunderbird. Then go into 'Offline' mode. Then copy all emails into suitable folders in the 'Local Folders' account. Emails in Local Folders do not synchronise with server. Once you have a copy of all your emails in Thunderbird on your computer, create a backup because when Hotmail stops your account, you will no longer have access to that account and all emails on server in that account will be removed by Hotmail. If the email address was one issued by Hotmail, then it will cease to exist when the account is closed. You may have a copy in Thunderbird, but when the account is closed by Hotmail, you will no longer get emails from the server and you will not be able to send either using that email address. Thunderbird is really going to be the place where you can store your Hotmail emails. Thunderbird can be set up to have several mail accounts accessing different servers. So if you created a gmail account or have an email address issued by your ISP, you can use Thunderbird to access all of these different accounts /email addresses and display all emails in Thunderbird.