Can the mobile phone check the contents of the mailbox by SMS? That is, the mobile phone does not need to connect to the Internet, and directly displays the email content in the inbox.

I don't have this at the moment. I have to check my email online. If you are a relatively new Nokia mobile phone, you can set up a mailbox on your mobile phone and display it directly in the SMS menu. You can set up multiple mailboxes at the same time. Unfortunately, it must be networked. But if it's just words, the traffic is very small and almost negligible.