[SadWebDeveloper]

Are you getting "DDoS'ed" from the DNS Server or from the HTTP Server?

Usually the later is more common since DNS tends to be a quite robust software to handle some levels of heavy the traffic (and the protocol being _lighter_ than HTTP).

Anyway you should separate the DNS Server from the Web Server, for this particular case personally i recommend "DNS Cloud providers" like AWS Route 53, they give you by default 4 different geo-located points and provides an API if you want to fight back the DDoS'ers (by changing your DNS records to 127.0.0.1 or 255.255.255.255 for a short period of time), usually these solve the email issue.

As for the web server, this is tough a well placed DDoS won't be stopped even Cloudflare have been hit with huge attacks that they couldn't handle (despite what their PR department says, the fact that even a bigger network than Cloudflare like Akamai couldn't protect Brian Kerbs tells you a lot about how tough these space is), best way is null routing the bad actors and spreading different ways to access your services like asking customers to go to frontendXYZ.mydomain.tld.