Not receiving emails from hotmail, but am receiving them from gmail.

Not receiving emails from hotmail, but am receiving them from gmail.

I don't know how many emails I've missed so far. I also don't know if this problem is restricted to hotmail-sent emails, or if other source domains are also affected. Can someone please look into this. 

(We are hoping to become a ZohoCRM user/reseller, but if Zoho Mail is as unreliable as it has been so far for my domain, it's not exactly a practical solution that we can sell to our customers with a clear conscience.)