email and mx records help

hosting is with hostgator and it has a sub domain multi site. im using domain mapping.

I have a client who has a domain with godaddy

I created an a record to point to my server like usuall but she also needs email

how do i do this? hostgator is clueless when it comes to multi site

godaddy email stinks so it would be nice if hostgator email can be used.

can i point the mx records from godaddy to my server and some how get mail?

in order to get mail currently i need to add the domain to cpanel and if i do that wouldnt that screw up the multi site portion for that domain?