What problems are you having?  If you are referring to the Mail app, for use with Windows 10 and 11, it is usable, but I think it is a bad idea to use it and I would strongly recommend Thunderbird instead.

I tried using it with GMail and, though deleting messages in the app means they no longer show in the app, they are still left on the server.  Over time, you would have an enormous number of messages left in GMail, I believe still in the inbox.  Wherever they are, they are just taking up space.

Since I only tried the program with GMail, I don't know what might happen with other servers but I wouldn't want to take the chance.

If you still want to try the app, let us know what problems you are having and we can discuss them.  For example, f9 is the command to download messages.

Gene