Custom Domain for iCloud Email

Is it possible to use a custom domain with iCloud email? I have an email address user@domain.com and I would very much like to send/receive from that account along with save messages to the iCloud. Is there any way to do this? I know I can setup Gmail to do this, but I figured there must be a way to do it with iCloud. I just want to have my email available on all my Apple devices.

Thanks in advance.