@anikasingh201611
There are no DNS records related to email found for this domain.
Domains that send email but have no MX record are suspect for spamming.
I assume this domain’s email is handled by your MiaB? If so, you need to enter the DNS records found on the External DNS page in the admin area to the DNS records at DigitalOcean.
EDIT: Or you need to change the name servers at the registrar to point to your MiaB as mentioned in another topic…