There are several steps to take to troubleshoot why emails may not be received on your mobile data:

1. Check your mobile data connection
2. Check the security settings of your email application and account
3. Make sure your data is turned on for the email application
4. Check that your mobile email provider supports and allows mobile data
5. Make sure your account is set up correctly with your provider such as POP3 or IMAP
6. Check that the IMAP/POP3 settings in the email application are correct