Email Will Not Receive

This is a just some kind of setting I think, I just need some help.  If Drew happens to get this....This is the domain I was having issues with a couple weeks ago, www.pabesthomeimprovement.com.    I built a site here, but the domain name is registered with Wix.  I was able to get "my" site up under the domain name.  My client wanted another email account, so I created one, it is mark@pabesthomeimprovement.com.  Well, I tested it that day to make sure it sent emails about, but I did NOT make sure it can receive them and as it turns out it can't.  My client just sent me a message letting me know he tried to send an email to that account and it comes back as "undeliverable."  I tested it and, yeah, that's what happens, but it SENDS out emails just fine.  Can someone shed some light on this please so I can get this fixed?  Thank you.