Email - Exchange and external ISP

Here's my configuration:
SBS2003 with Exchange
Externally hosted ISP ( for mail with Exchange set up to pull POP3 into local mailbox

One person in the company needs to receive/send email from the company email address.  I set him up on our external ISP as  He can receive/send email just fine - as long as it is from somebody outside our company.

When another employee sends him an email (i.e. from to, the server thinks Sam is an internal exchange client and cannot resolve the address.  I do not have Sam set up as a user on the server.

Anyway to force internal email to route to the external ISP?  Or do I have to set Sam up as a user on the server and give him OWA access??
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dmessmanConnect With a Mentor Commented:
"It matters because they did not want to give this user any access on the server"

You can easily remove access to all file shares for this external user if you'd like.  They can have an Exchange mailbox and access to nothing else.

But if we want to keep it the way we have it . . .

The real problem here is that your SBS box thinks it receives mail for your domain.  It's listed as one of the recipient domains.  The mail isn't going to your ISP because your server knows that it is a server that should be receiving that mail.  Here's a lame option:
Set up some kind of alias domain on the external user's mailbox.
For example - if your domain is and his address is - give that mailbox an alias of on the ISP's server.  

set up forwarding for the external user's on your SBS box so that all mail sent to is forwarded to

I can't think of another resolution given the way your server is configured.
I'm confused as to why this matters.

User 1, user 2, and user 3.

Each user has an Exchange mailbox on the ISP's POP server.  Each user has a local Exchange mailbox.

Every 15 minutes, the Exchange server pops the ISP pop server and brings mail to the Exchange mailbox.

What's the difference if user 2 sends mail through the ISP's mail server and eventually ends up in the Exchange mailbox that way or sends it directly to the Exchange mailbox?  

As many other people will probably say - I'd recommend moving your mail processing to the Exchange server.  That's what it's there for and it works great.  There are other means for ensuring mail delivery in case of an outage.
lbitAuthor Commented:
It matters because they did not want to give this user any access on the server.  Why I don't know.  So this one user does NOT have a local Exchange mailbox.  He only has a mailbox on the ISP's server.

And yes, I realize that it is recommended to move mail to the exchange server.  But not an option at this point.
Rajith EnchiparambilOffice 365 & Exchange ArchitectCommented:
Give the user a mailbox and that will solve things easily.

Why treat this user any different to others? What is the issue?
lbitAuthor Commented:
Thanks - good solution.  Before I do that, think I'll try again to get my client to 'allow' them on the server.  I am not sure exactly why they are so worried about this.  But if not, tested yours and it works.
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