Migrating from External POP3 to Internal Exchange 2003

Ok I'm not sure if this is possible. We have a customer with over 100 users, currently getting their mail through an externally hosted POP3 Service Provider. They want to migrate to Internally hosted Exchange 2003. I will be the only one doing this cutover so it would be very difficult to visit every workstation and change all the outlook clients to point to the new exchange server in one night.

My question is, does anyone have any recpomendations, or is it even possible to have some users accessing email through Exchange and some still accessing email through the externally hosted POP3 server.

I was hoping to configure Exchange to pull mail from the POP3 server until I can get each workstation pointed to the exchange server. Then go ahead switch over the MX record, and remove the POP3 functionality of exchange. I am not sure if Exchange can pull email from the POP3 server on an account by account basis. Or if Exchange simply pulls all the mail off the POP3 server at once

Hopefully someone has doen this before and could lend a few encouraging rods of wisdom.
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mickinoz2005Connect With a Mentor Commented:
What version of Exchange do you have i.e is it full exchange standard or SBS exchange (yes they are the same but with some slight variations)

In sbs there is a pop3 connector and you can pull individual pop accounts into exchange and allocate the email to individuals.

To be honest from a managment poing of view and the headaches it is going to cause I would just try to knock it all on the head in one go.

Once you put the users on the exchange unless they are connecting to their own pop3 they are not going to get mail as you will have some others still using pop3 therefore you can't do an mx pointing and you can;t do a catch all account.

If you used something like policymaker from Desktopstandard you could roll out all the profiles in one login, which would solve alot of your problems however for 100 users thats alot of cash.

The other option is you change over the users to mx first setup exchange with the mailboxes etc and let the mail start coming in, then over a day or two go around changing the profiles and in the meantime any user you have not go to just uses OWA (outlook web access) to access their email. Therefore they are all using exchange straight away.

The other point just that i thought of do they use pst files for storing their mail at the moment cause if they do you will have to exmerge them into exchange.


SembeeConnect With a Mentor Commented:
100 users is a big ask.

What sort of time scales are we looking at? Can you spread the work out over weeks?
Is it just you?

Where can you take pain? There will be pain.
Internal email? Ability for users to email each other?

I would steer well clear of the POP3 connectors. That isn't really going to achieve anything. I suspect that you have 100 POP3 accounts, so all of those accounts will have to be entered in to the POP3 connector to receive email.

Local email will be stored in PST files, those could be anywhere and the content needs to be imported in to the server.

With smaller sites I do it in one hit, or have a period of parallel running - where the users collect email from both the POP3 and Exchange server. The reason you cannot do that is because you cannot visit all the users in a reasonable time frame. I can move 20 or 30 users in a day using parallel. 100 would take a good week. During the parallel running period email could be going to either POP3 or Exchange, so you could have users not getting email for five days.

Therefore I see it as one of two ways, depending on how co-operative the ISP is being.

1. Big bang.
New accounts all set, new profiles created by scripts etc etc. Users loose old email until a visit by IT to their machine to import the contents of the PST file.

2. Slow and gradual.
Accounts are created as you migrate. All email is delivered to the Exchange server, then pushed back out to the ISP for those whose accounts haven't been moved.
As you migrate the users, you first mail enable their account and add them to any groups. Then visit their machine, remove the POP3 connection and configure it for Exchange. Finally import their PST file in to Exchange.
The only users visible in the GAL will be those that have been migrated.
It is key that the account is created for the user on Exchange first, so that Exchange starts collecting email for that user. You want to ensure that there is no email on the user's POP3 mailbox when you remove the connection.
You also really need the ISP to be co-operative and be able to put some kind of forwarder on to the accounts to send email back to your Exchange server - so that anyone who hasn't been migrated and sends email via the ISP the email is delivered.

Variant to option 2 is to configure Outlook to connect to Exchange, and then add the POP3 account back in immediately. Run both systems on all users until everyone has been migrated to Exchange, then visit every machine to remove the POP3 account (which shouldn't be collecting email).

If the ISP isn't co-operative, then you may have to change the SMTP (outbound server) on all accounts to be the Exchange server before you start the migration. It is the only way to ensure that all email gets delivered to the correct mailboxes - whether this is the Exchange or POP3 mailbox.

Where can you take the pain? Its going to be messy.

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