Unable to update the email Id

We are not able to change the email inner account as our corporate email has moved to a new domain. We tried several times to change the email from admin@texasadmissions.com to info@texasadmission.org but it is not letting us change. We get a continuous message that enter a valid email. This is a valid email. Any help here will be highly appreciated.

We tried checking the email but could not find any MX records related to it. Could you please verify if the email spelling is correct.

Also, the current email id's domain is a different one in your account.

Looking forward to your response.

Thanks.