This time I found a problem in the process of adding a domain on Zoho mail service, The problem is enough to make me confused. I want to add a domain with a domain name  vectortshirt.com, but when I add the domain, I get an error message  "This Operation has been restricted. Please contact support-as@zohocorp.com for further details". But if I add another domain name, for example:  blabla.com, I don't get the problem.

One more, which makes me confused is when I try to add the domains with keywords TSHIRT, would always get a similar message  "This Operation has been restricted. Please contact support-as@zohocorp.com for further details".