Yes I use an email client - Thunderbird and Outlook, and both can send emails to
name@server.domain.com, but both get return to senders when sending to
name@domain.com. When I send either from mailx or from thunderbord they arrive as
name@server.domain.com
I am using Maildir, Postfix and Courier if that makes a difference.
As for the user mail clients setup, I do have ISPconfig installed but do not use it, as I really don't see the point since I just wanted to setup a working mail server, so.... I just create users with adduser and then send an email to that
user@server.domain.com and tada, Maildir is created and that user has a mailbox.
Hope those answer the questions you had, thanks for the help!