Need to make exchange server allow access to external POP3 server


I am the administrator for a group of users.  The network consists of several Windows XP systems and a server running Windows 2000 Small Business Server.  They use Exchange on the server primarily for shared calendars, although they do use Exchange to store their e-mail on the server.  For e-mail, they utilize an external Internet service provider for POP3 e-mail boxes.

Everything works fine except for one user (we'll call her who works remotely and does not have access to the network.  At first, this user did not have an Exchange account, but she did have a POP3 account at their POP3 mail server (I'll call it "") to check her e-mail.  The first problem occurred when users within the network tried to send her e-mail.  The Exchange server rejected their e-mails with the following message:

The following recipient(s) could not be reached:
            The e-mail address could not be found.  Perhaps the recipient moved to a different e-mail organization, or there was a mistake in the address.  Check the address and try again.
            < #5.1.7>

This occurs because the user doesn't have an Exchange account, but she does have an external POP3 account, and it looks like Exchange won't let the mail go out to the POP3 server if it can't find an Exchange mailbox on the server.  My question is, how do I fix this?  I've tried adding an Exchange mailbox for the user and I get a different problem, which is that Exchange grabs all the mail sent internally to her on the network (rather than utilizing the external POP3 server), and, because she doesn't have access to the network remotely she can't check her Exchange mailbox (we don't have VPN set up at this point).  Any help with this would be most greatly appreciated.


John Sheppard
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Let us clarify one few things.
You said she does not have an email address within your organization ? correct ?
is your domain is i.e

what is the domain name for the external mail server ?
Who accepts mail for your organization ? meaning who accepts mail for your domain, you or the hosting company  if an email sent out out to you?

John_SheppardAuthor Commented:

She has an e-mail address on the external POP3 server.  The domain, for the purposes of this discussion, is  The name of the external POP3 mail server is and is administered over the Internet (it's not on the local network).  Mail that is sent to the organization from the outside will be collected in POP3 mailboxes on the external mail server.  It's just e-mails within from one member to another get handled by Exchange without the external mail server getting involved at all.  When sending to the user in question (, if she does not have an Exchange mailbox, the Exchange server will (because it assumes it has complete control over and doesn't know about the external mail server) cause the e-mail to bounce back rather than get forwarded on to the POP3 server where she does have a mail account.  I'd like to change that behavior so that when Exchange sees a mail address it doesn't recognize as being on the Exchange server (but still is a mail address) to go ahead and forward it on to the external POP3 server.
Here is my reply to you if I understand correctly.

Email sent to you goes to the external site and your users POP their emails from that server.
The external site collects all emails sent to anything going to
Your internal exchange server domain address called *
She ( that user) does not have internal local account.

Here is what I think
>the external POP3 mailserver is accepting all mail sent to * Your organization use POP3 protocol to recieve their mail from all external
> is not your domain name but rather your mx record, which is different from the domain name. the mx record is how you tell everyone outside on where to deliver to emails going to *
> you have set your internal exchange server to use domain called *
>your users use GAL to send an email to that user typing full name ( and she is not part of the users they can select from the address book.
>Even if you type full address to send email to her, you will receive bounce back email like you did in above. Anytime you send an email that has your internal domain association, it gets checked @ that domain to see if that user has mailbox which in this case she does not.

If you want to resolve this, here are few options:
Option One
you can give your internal exchange server another proxy address ( different SMTP address) other than * This way all emails you send to * will be accepted by your external POP3 mailserver, and when you send email to that user it will still be delivered.
Option Two:
Create mailbox for that user in your exchagne server, open port 110 on your firewall and let that user POP her emails from your server instead of the POP3 server. This way, se will receive all emails.

Option Three

Let your exchange be the your mx record and dump the POP3 server completely. set OWA to have that user and all other users connect to your exchange server when they are outside the office.

That is alot of typing,

Shepard read this and if u have any questions do call back.

I will explain briefly.U have a hosted domain called
that ur users use pop3 to download their emails.U also have an active directory domain called with the same and this will have no problem except when u have external users.When u create that user and ur local users try to send emails to that person exchange will not allow that mail to leave ur exchange.Well that is by design and any email for any domain that ur exchange is responsible for will not leave ur exchange.Read the artical it will give u a solution.

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The problem appears to be that the exchange server thinks it handles all mail for the domain, when in fact the isp's mail server handles mail for other users in the domain that exchange doesn't know about.  The solution is simple.  

You need to tell exchange to send mail with unresolved recipients to the ISP's mail server.

Start -> Programs -> Microsoft Exchange -> System Manager -> Admin Groups -> First Admin Group -> Servers -> SERVERNAME -> Protocols -> Smtp -> (right click) Default virtual server -> Properties.

On the Messages tab, enter your ISP's mail server in the "forward all mail with unresolved recipients to host" box.

Good luck, let me know if that helps.
Ejay Hire at hotmail dot com.
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