There is a command group 'az_communication_email_domain_sender username'. This group of commands could 'manage communication email domain sender username'. The group of commands has global parameter '--debug' which means 'Increase logging verbosity to show all debug logs.'. The group of commands has global parameter '--help -h' which means 'Show this help message and exit.'. The group of commands has global parameter '--only-show-errors' which means 'Only show errors, suppressing warnings.'. The group of commands has global parameter '--output -o' which means 'Output format.'. The group of commands has global parameter '--query' which means 'JMESPath query string. See <a href="http://jmespath.org/">http://jmespath.org/</a> for more information and examples.'. The group of commands has global parameter '--subscription' which means 'Name or ID of subscription. You can configure the default subscription using `az account set -s NAME_OR_ID`.'. The group of commands has global parameter '--verbose' which means 'Increase logging verbosity. Use --debug for full debug logs.'. This group contains a child command 'az_communication_email_domain_sender username_create'.The syntax is: az communication email domain sender-username create --domain-name
                                                     --email-service-name
                                                     --name
                                                     --resource-group
                                                     [--display-name]
                                                     [--username]. The 1th example of the child command would be to use it to 'create a sender username', the syntax is: az communication email domain sender-username create --domain-name DomainName --email-service-name ResourceName -g ResourceGroup --sender-username SenderUsername --username Username --display-name DisplayName. The parameter '--domain-name' is required. It is used to the name of the domains resource.. The parameter '--email-service-name' is required. It is used to the name of the emailservice resource.. The parameter '--name --sender-username -n' is required. It is used to the valid sender username.. The parameter '--resource-group -g' is required. It is used to name of resource group. you can configure the default group using `az configure --defaults group=<name>`.. The parameter '--display-name' is optional. the display name for the senderusername.. The parameter '--username' is optional. a sender senderusername to be used when sending emails.. 