Hi, Lewis. You can definitely do most, if not all, of what you mention below. Note that I'm *not* a RoundCube guru by any means, just a user, so take things with a grain of salt. I'll comment in-line.
On 2014-12-09 04:32, Lewis Butler wrote:
I have Roundcube installed on my web server to access the accounts on my mail server.
What I would need to be able to do is have him load up a roundcube instance on my machine and then… login with his account info for the third party host? I mean, it seems as this would work if Roundcube is essentially acting as an MUA, but is it?
Roundcube will happily talk to an external IMAP server. Set $rcmail_config['smtp_server'] = 'YOURIMAPHOSTHERE'; in config/main.inc.php
I am assuming this would have to be an entirely different Roundcube install just for him.
Yes.
Oh, and if possible I’d like to setup this instance of Roundcube so that only his account is allowed to try to login to the third party provider. I don’t want to become an alternate webmail for everyone else.
This is, I believe, possible, but you'd have to store his password locally (I think), and if it changed, it would stop working. Though... looking at main.inc.php, I wonder if you couldn't just hardcode his username. I leave that to you to experiment with. ;-)
Good luck!
-Ken