I don’t have access to my network, can I still use Mail?

Yes. If your phone supports Wi-Fi, you can use Mail as seamlessly as using your network. If you cannot connect to your network and you do not have access to Wi-Fi, you can use the Mail application in offline mode to interact with a cached view of your accounts.  You can read mails stored on the phone and write new mails. The mails will be sent when your network access has been restored.