Can someone explain to me what the mx field passes? I have domain.com and www.domain.com as cname for tomato.domain.com. Then I have tomato set ddns a record for tomato.domain.com. I have mx record set on my dns, zoneedit, for tomato.domain.com (since domain.com cname's to tomato.domain.com) for primary as itself (tomato.domain.com) and secondary as ddwrt.domain.com (where I have my second router with failover wan). So since everything is set up on zoneedit like so, I take it I can leave mx field in tomato blank?