We have an offsite hosted email server, which works (but is slow), and all our users connect to it to receive email.
Internal users connect to my postfix server to send email, I want to leave that there and create a new email server that can act as a inbound relay (Not sure if that is the correct term) so that internal users can connect to it instead of the remote one:
Ext Server: -> POP/IMAP/?? -> Int Server -> IMAP -> Users
I'd basically like to mirror all email from the hosted server internally, so users can access it via IMAP. Allowing me to back it up! (Hosting company organized by consultant who manages it through a third/fourth/fifth??? party, gah) And filter spam/virii/etc..
Is there a way for users to log into my server, which then logs into remote server and downloads email to itself, then delivers via IMAP to them? Or am I overthinking/confusing/breaking something here?
What would happen if I sent an email to myself? Would it go out to the hosting company and then back in? Ideally only certain users would need to be on the hosted server, could I set it so that internal email gets delivered locally, but certain users get delivered to hosted server? Its 1630 on Friday, so maybe my brain is fried. I'll probably think of a hundred things wrong with this by Monday, but I want a second opinion.
Just thought of something, I can set a forwarder for all the users who are ONLY EVER INTERNAL, and get their messages forwarded to my server.. hmmm.. that could work! I'll have a play and see what happens to a few test users.
EDIT: Nope, either DNS is fubar, or the remote server won't send email back to the server that sent it.. would probably create a loop anyway. Bad idea.. :-(