I was able to fix the error:
1: Bought private email from Namecheap
2: My Domain name Nameservers were pointing to Digital Ocean
3: I set the MX, CNAME, TXT and SRV from namecheap private email to Digital Ocean since I linked my domain to the droplet.
4: On Kobotoolbox account I made sure super admin email is the email I had purchased.
SMTP set-up onfigurations:
EMAIL_HOST=mail.privateemail.com
EMAIL_PORT=587
EMAIL_HOST_USER=youremailaddress
EMAIL_HOST_PASSWORD=youremailpassword
EMAIL_USE_TLS=True
DEFAULT_FROM_EMAIL=youremailaddress
This worked for me hope it helps someone else who is facing the same.