Linux – n open source email client that will work with Exchange 2007

1. Yes you can continue to use your 03 box as a mail server. You can also have it as your "SMTP Gateway/Transport" still if it is where all your email comes into from the internet.

2. OWA will be tricky since you can only have it pointing to a single server. So existing mailboxes on the 2003 box won't be able to use OWA until they are migrated (unless you go through a big ordeal that I don't want to describe here).

3. You will need a certificate for Outlook Anywhere. Regardless, you'll need to setup autodiscover.domain.com DNS records externally for Outlook Anywhere to work properly automagically.

Things to note from our migration:

-Blackberry stuff can be tricky, move the BESAdmin account first. -Activesync relies on the Client Access stuff, so either move them all first, or all last. This will affect OWA though since the same rules apply. -if you have a small enough company (under 500 people) I would strongly recommend moving around 25-50 on a weekend, let them test throughout the next 2 weeks, then move EVERYONE else in a single weekend. -you shouldn't have to mess with their outlook profiles -Migrate resource mailboxes over and then convert them to true "resource mailboxes" using Powershell and OWA

The things that I remember vividly is that OWA/Activesync definitely broke if you moved it over to the 07 box first. So we ended up moving all of the OWA/Activesync users at the same time and then moving the firewall rules to redirect to the 07 box.

EDIT: I'm referring to what happens to OWA if you only have a single Exchange 07 server and don't bother to setup 2 different URLs and redirects for OWA clients. See the technet article I refer to in the comments below.

The bad news is that there isn't any decent Exchange clients for Linux, other than possibly some crap connector for Evolution that will only compile on Suse.

The good news is that starting with Exchange 2007, there is a SOAP web-services interface for Exchange, so it's now feasible for somebody to actually write a client, which wasn't the case with MAPI. Microsoft is updating its Mac email client and Apple is providing native support with Snow Leopard, so something should pop up one of these days.