If you have been trying to open an email or reply to/forward an email from your Nokia Mail account before synchronizing your account, then the Mail application can stop responding. If this happens, please do the following:
1. Set the phone to offline mode2. Remove your Nokia Mail mailbox from the device by performing the following steps: Go to Mail and select Settings, press and hold Nokia Mail mailbox, and choose Delete Mailbox.3. Turn the phone off4. Turn the phone back on5. Set phone back to online mode6. Re-create your Nokia Mailbox by performing the following steps: Go to Mail, select New Mailbox > Nokia Mail and sign back into Nokia Mail.
Don’t worry, this process does not delete your emails, it just resets your mailbox.