e-mail re-routing (same domain)

Hi Everyone,

Bit of a dilemma here...we're an ISP. Our Internet customers share the same email domain name as our internal employees.

Currently all those e-mails use our POSTIX e-mail server. We want to have our employees' e-mail to route through our Exchange server, while keeping our customers on the POSTIX. Again, all e-mail addresses use the exact same @company.com domain name.

Is there any possible way to separate the traffic like that?

Thanks in advance,

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This is possible using email forwarding.  All email must for a single domain must be received by on email server and then can be forwarded to other (like Exchange and or Postix), or you can utilize either one of those current machines to receive all the email and forward the approproate accounts to the other.  
Once you decide on the flow, you can determine the best method of fowarding.
To help decide, reviewing "Exchange front vs back end servers" and also look into Unix mail server configuration options (easier than Windows in most cases).  Having a front end email server as Exchange or Unix sendmail will also provide different options going forward.
TheodosiosAuthor Commented:
Okay, if I understand correctly, we'll need 1 e-mail server on the outside perimeter, either Exchange, unix or barracuda, which, based on e-mail address, will forward e-mail traffic to either the Exchange server or the POSIX server?

If so, I'm assuming we'll have to set up a separate forwarding rule for every e-mail account? Currently there is really no distinguishing feature between employees e-mail addresses and customer e-mail addresses.

Also, assuming all the above is possible, is it "recommended?" To me, it makes more sense to actually have a create a separate domain name for both.


I would have suggested a seperate domain name, but your quesiton indicated using the same one.

If you were using all Exchange servers, the front end server automatically knows which backend exchange server to send the email because this information is contained in the Active Directory.

Again, if you have a single Exchange front end server and one backend, it may be possible to send all other emails to a alternate email server (not Exchange) to be processed and you would not require any individual forwarding rules (maybe just the one catch-all mailbox).
This will even work for having a single Exchange server.

Here are some other alternative methods:


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TheodosiosAuthor Commented:
Great, thanks for all your help.


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