I talked to Doster and was told for DNS management to work, I need to use these nameservers:
NS1.NAMERESOLVE.COM
NS2.NAMERESOLVE.COM
NS3.NAMERESOLVE.COM
NS4.NAMERESOLVE.COM
So what they're saying is, I cannot use Google Mail on my domain and externally host my website on, for example, Blue Host, because I have to be using those 4 nameservers for DNS management (to use Google Mail MX records) to work?