I have a DNS + Mail service with hosting company HostA for a domain mydomain.com and would like to use the servers of FreeDNS as nameservers so that they will resolve web requests to my home server's dynamic IP.At the same time however I don't want to host myself the email but use the mail servers at hosting company HostA, so I can download my info@mydomain.com mail.I thought this was a simple matter of adding a nameserver record which pointed to FreeDNS  and a MX record which pointed to hosting company HostA domain.However they tell me either I use their nameservers for both web and email or I must use FreeDNS nameservers and I cannot edit the MX record anymore but have to deal with it at FreeDNS website.Is it true? can you explain me why?
Separate Nameserver and MX server at different providers
dns;dynamic dns