Error 553 (Relaying disallowed)

Error 553 (Relaying disallowed)

I have been sending emails and getting replies to my email address. However, none of the replies can be seen in my inbox. Upon learning the reason for this I tried making an mx record entry on my domain host. Once I did that, when I sent email to my email address on zoho account from my gmail account, I got Error 553 Relaying disallowed. Need to resolve this urgently. Please help.