User283571144 posted
Hi barakkadosh,
According to your description, I suggest you could consider using asp.net signlar and identity to ahcieve your requirement.
You could use signalr to send the message and identity to let user login.
More details about how to use signlar send message, you could refer to below article.
https://www.codeproject.com/Articles/1221913/SignalR-Chat-App-With-ASP-NET-WebForm-And-BootStra
More details about how to use identity in webform, you could refer to below article.
https://docs.microsoft.com/en-us/aspnet/identity/overview/getting-started/adding-aspnet-identity-to-an-empty-or-existing-web-forms-project
Notice:
If you don't allow user reply the message, you could remove the send message back button according to the user's role.
To achieve this, you could use identity role manager.
More details about how to use identity role manager, you could refer to below answer.
https://forums.asp.net/post/5806566.aspx
Best Regards,
Brando