After setting up the Free Email Service for your domain name, you need to modify nameservers to the ones specified by ProjectArmy. In most cases, it may already be set automatically.
Generally, the Free Email Service should start working within 24-48 hours after modifying nameservers.
Don’t be alarmed when you encounter an error while using some DNS Tools like DNSReport.com:
No NS A records at nameservers
Everything should be working correctly once nameserver changes propagate.