Two question about Fetch, get unread mall & set mail read

1、How to set mail read? Maybe is setFlag function, But I need example code. 2、How to get unread mail list? getRecentMessages is not useful , Always get null

If topic is not obsolete, I want to say:

1. I found out that Fetch set message read automatically on every Message class constructor invocation. However, for me it worked perfectly only for IMAP servers. For POP3 I am struggling with it now.
2. Server class has getUnseenMessages method

It turned out that POP3 protocol does not support message flags at all :)