Hi @Gana S ,
To resolve the issue of being unable to send mail from WordPress using Azure Communication Services, you need to ensure that you have valid sender usernames configured under your custom domain in Azure. The "Invalid email sender username: 'info'. Please use a username from the list of valid usernames configured by your admin" error message indicates that the sender username 'info' is not recognized, which suggests that it may not be included in the list of valid usernames configured by your administrator.
If the valid sender username list is empty, you need to add a sender username that is allowed to send emails. Make sure that the sender username you want to use is created and verified in the Azure portal. You can follow the steps to add a sender username as outlined in the Azure documentation. https://learn.microsoft.com/en-us/azure/communication-services/quickstarts/email/add-multiple-senders?pivots=platform-azp
If you haven't already, you may need to create a custom domain and configure it properly to allow sending emails from WordPress using Azure Communication Services.
https://learn.microsoft.com/en-us/azure/communication-services/quickstarts/email/create-email-communication-resource?pivots=platform-azp
https://learn.microsoft.com/en-us/azure/communication-services/quickstarts/email/connect-email-communication-resource?pivots=azure-portal
Hope this helps, please let us know if you have any further queries.