So if you are using URL / Domain Forwarding to forward your Freenom domain to your 000webhostapp URL you can get email features by setting the MX directly at your domain registrar (Freenom).
Simply login to Freenom.com
Manage the domain
Select Manage Freenom DNS
Enter the two MX records provided by your email provider.
In this tutorial we are using the MX records given by free email forwarding tool ImprovMX.
Simply input the values given to you by the different services ImprovMX, Zoho, GSuite etc.
Give it half an hour and it will likely have propagated else give it up to 48 hours, ImprovMX panel will let you know when it is working (or your selected provider)
Ensure you get the success message!