Not able to create DNS Options and Save DNS Records

Operating system: CentOS
OS version: 7
Hello

I am Not able to create DNS Options and Save DNS Records, please check the attachment. In DNS Options I want to change the “Allowed sender hostnames” to webmail2.abc.in after doing the changes it will show the old entry only.

https://www.virtualmin.com/system/files/issues/1_2.png
https://www.virtualmin.com/system/files/issues/2_2.png