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Migrating from GroupWise to Exchange 2007, over SMTP – Flat Forwarding

One of the challenges I had more recently with a migration from GroupWise to Exchange was specifically with users existing in GroupWise and users that have been migrated from GroupWise to Exchange. The scenario is, when users still exist in GroupWise, how do they email users already migrated to Exchange? The best approach, with minimal impact to the users is to continue utilizing the GroupWise address book and to also not lose frequent contacts historical information.

The challenge with maintaining the existing address book is how we represent the users and how messages flow forward to Exchange. If you have experience with the GroupWise connector for Exchange 2003, you know that contacts appear within GroupWise for migrated users. Those contacts send all messages to the API gateway, created for this connector. Well, in Exchange 2007 (without Exchange 2003 coexistence) SMTP mail delivery is the most optimal approach, between coexisting environments.

Because we are using SMTP mail delivery, we wanted to forward all messages going to the old GroupWise mailbox, to the new Exchange mailbox. However, when this occurs, the message does forward to the Exchange mailbox, but appears as an attachment from that person’s mailbox. (Example, GroupWise UserA sends to migrated GroupWise mailbox UserB. UserB receives the email in Exchange, but looks like it came from themselves UserB.) GroupWise is unlike Exchange, in which you cannot setup forwarding on the mailbox, without it looking like a forwarded message.

We found a solution to work around this problem. Our solution was to use a “Flat Forwarding” option with GroupWise. Flat forwarding is supported on a GroupWise Internet Agent (GWIA), but not necessarily (easily) on a per user basis. Our initial thought on flat forwarding was to direct each Domain/PO to the flat forwarding GWIA, when the users were migrated. However, that wouldn’t work because we couldn’t always plan for everyone to be migrated in a single Domain/PO. So our work-around for this was to setup flat forwarding on a specific GWIA and to direct each mailbox to that PO, by adding the GWIA address to their forwarding address. As an example: in the GroupWise client, normally forwarding would be setup as such: forward to UserB@exchange.smtpdomain.com. To support flat forwarding, we added the following to the SMTP address: GWDomain.FFGWIA:UserB@exchange.smtpdomain.com. The GWDomain.FFGWIA is the domain in which the GWIA exists, followed by the Flat Forwarding GWIA connector.

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