iRedMail, GoDaddy, and HostGator

I have iRedMail for my mail hosting, but have just gotten hosting through HostGator. I set the MX settings and the @ settings in godaddy to point to my iredmail IP, but now wish to know how I would point the web hosting elsewhere. So when I type in "mydomain.com" it goes to my website, but when I type in 'mail.mydomain.com' or 'mydomain.com/mail' it goes to my iredmail login.
I'm new to all this, so any help would be awesome.