Ok, my Question now. Is it possible to implement Email system special for users of an anvil application using “Custom Mail Server” and “Custom Domain”.
We would prefer it if you started a new topic if you have a new question, this makes it easier for people in the future to search for questions similar to yours and find the answers that were previously given.
It helps everyone out that way 
[I went ahead and moved it since I had closed a new topic you/they created previously.]
Yes, the custom mail server can send email from addresses on your custom domain and handle emails sent to your custom domain.
As I think about your question from the other thread, though, using such emails as the back-end of a chat application doesn’t strike me as a good idea. For one thing, it doesn’t solve the problem of notifying the client-side code when a new message arrives. (For that, I currently use “polling,” running a server function every 5 seconds or so to check for new messages. But there may be better ways, such as those proposed in the other thread.)