When you access you mailbox via POP protocol, your email messages will be downloaded to your local computer / laptop and the email messages on the server will be deleted by default.
The question is can we leave the messages on the server until we delete it or at a specified time? The answer is yes we can. This tutorial shows you how to leave email messages on server in Mozilla Thunderbird.
Let’s go to the guide:
1. Run Mozilla Thunderbird program
2. Click menu Tools > Account Settings
3. In the Account Settings, click Server Settings under your email account.
4. Tick the ‘Leave messages on server’ option. For example you can leave the messages on the server for at most 7 days then it will be deleted automatically. See image below:
5. You are done