Can't receive emails, but can send

Can't receive emails, but can send

I setup a mail using the domain @shopik.io. I set this up using the correct CNAME record on Namecheap. When I tried to send a test mail from my Gmail account it was not able to send and I got the following error;

The response from the remote server was:

554 5.1.1 <xxx@shopik.io>: Recipient address rejected: undeliverable address: host mail-outgoing-fef.relay.svc.cluster.local[10.27.5.108] said: 554 5.7.1 <xxx@shopik.io>: Relay access denied (in reply to RCPT TO command)

I was able to send an email from zoho to Gmail, but not the other way round. How can I solve this issue?