[exim] imap use after exim

Hi, I recently got my exim server working. I have no issues of my
current setup and i'd like to know if the following can be done.

I have a username that needs to have his sender mail copied/stored so
that imap can present it later. (it can be an example for mbox or even
maildir format, the imap server looks at both mailbox formats in ~ and
in /var/mail without issues)
This particular user has no problem accessing two email client software
from separate machines to access the esame email sent to him, but mail
he sends out don't get a copy for imap..

I believe this can be done, but i'm sort of stuck as how to go about
it.. Maybe a point to a documentation link or a small sample that can
provide me what keywords I can check out, I'm getting quite acquaint
with exim's setup (spent a long time learning how it's configured from
scratch).. so any snippet would do.. Thank you for any reply, greatly
appreciate it..