Prerequisites:
Domain name
Troubleshooting:
How old the domain is?
The domain should be a month old. You can check the age of the domain on the global site https://www.whois.com/.
Input the domain name and click whois and check the registration date.
Is the domain listed anywhere?
You can check the same on https://mxtoolbox.com/.
Click on Blacklist and enter the domain.
i) If it is listed in Baracudda please dont allow ask the client to Delist it.
ii) If it is listed in Spamhaus please dont allow ask the client to Delist it.
iii) If it is listed in any other 1+ place apart from Baracudda or Spamhaus then dont allow ask the client to Delist it.
iv) If it is listed in any other 1 place apart from Baracudda or Spamhaus then you can allow but inform the client to delist it
Is the domain having a website?
The domain should have a proper website with about us, contact us, privacy policy page etc. All tabs should be clickable.