Processing emails for multiple accounts using POP3

suppose I want to process emails for multiple accounts using a tool like OpenPop.net or any other tool. I.e.

Check the server for new emails for a give number of accounts
copy sender,recipient,subject etc into a database.

How do I access these emails t开发者_运维问答hrough code without having the user supply username and password? That is, is there a way that the application can access and use the Mail server user database, access the login credentials for each of the specified users and use them to retrieve their emails?

If not, how else would I go about this? I'm looking at a scenario where I'm able to process emails when they come in even in situations where the user doesn't login.

If the account has a username and password, and you access it over POP, it will require authentication.

There may be a way to access the email database directly but this would depend on the mail server in question.