I have given my server server1.domain.tld as the name. So then i created the A record and the MX record. Everything is fine as i'm able to hit my website and send and receive mails.
I now want to add a second site to ispconfig. I know I have to create a new A record to point the new domain over to my ip. Now about the MX record, is it as easy as just creating a new record to point to the new domain? Or is it more complicated.
Note: I'm not running my own DNS server because i have dynamic IP. I've created the two domains, along with the corresponding subdomains, on my free DNS server and I'm running a dynamic ip client to update the DNS servers.