When setting up em Client..... you have to use a email address to do so or it won't work. So I don't know what you did when you first ran/open the software.
Next thing is; is the the free version or the paid version. There's no support for the free version. If you have the paid version.....their techs can walk you through your issue.
If this is the free version.....I would uninstall em Client and reboot. Upon restart, would download a fresh copy of em Client and install software. This time let the software setup the email account for you. To do this is just input the email address you want to use.
Next thing is; is the the free version or the paid version. There's no support for the free version. If you have the paid version.....their techs can walk you through your issue.
Replying to an email.....if your are actually replying to emails....your are in fact sending them. Unless they are just being stored in the saved folder. I have no clue.
What are ISP details? When setting this up all you need is a email address. That's all I had to do.
This sound like you manually setup the email account.....and this is where you're having issues.
If this is the free version.....I would uninstall em Client and reboot. Upon restart, would download a fresh copy of em Client and install software. This time let the software setup the email account for you. To do this is just input the email address you want to use.