Arguably the best feature introduced in Outlook 2010 was support for multiple Exchange mailboxes within a single Outlook profile.
Before we begin discussing that feature, let’s introduce a couple of concepts. The first is called "message fidelity". It’s fun to say. :) The basic concept is that a message created by Outlook can have many attributes associated with it: custom forms, importance, rights management, categories, follow-up flags, voting buttons – the list goes on and on. These attributes are not, strictly speaking, part of the message – they are part of the envelope (carrying on with the metaphor of a postal message). In order for a message to have full fidelity, it must be created by Outlook, sent via MAPI, processed by Exchange, received via MAPI, and displayed by Outlook. If anything non-Microsoft gets in the way, there will likely be a reduction in message fidelity. That is, “something” may get lost.
Note that message fidelity is a pretty technical topic and is dependent on many variables. There are things that can be done in order to improve message fidelity when using non-Microsoft solutions. That being said, they are not configured by default and your average user will probably not be aware of those options.
The next concept is the idea of a “primary mailbox”. Traditionally, Outlook treated one mailbox connection as the primary connection. It was through the primary connection that all calendar reminder and task reminder notifications occur. It was also through the primary mailbox that all new mail notifications occur. This means that if you had multiple mailboxes being accessed through your profile, only one of them would receive notifications for new mail, calendar reminders, and task reminders.
In versions of Outlook prior to Outlook 2010, any Outlook profile was restricted to having only a single Exchange (MAPI) mailbox entry. And, if you had an Exchange mailbox entry in the profile, it was always considered the primary mailbox entry.
Now, Outlook did (and it still retains these features) have a couple of other features that allowed you to “work around” this limitation. First, it was possible to open additional connections to your Exchange server(s) using either IMAP or POP3. This was possible within the same profile. However, there were serious limitations associated with this. IMAP and POP3 don’t retrieve messages in full fidelity. These additional connections were also not treated as primary mailboxes. Also, IMAP and POP3 only support email – therefore calendars, tasks, contacts, etc. have to be in local storage (a PST file) and can’t be accessed from anywhere else.
Secondly, Outlook does allow a profile to specify to “open additional mailboxes”. These are mailboxes that the opening user has “full control” permissions to. However, these are not primary mailboxes. Therefore calendar reminders, task reminders, and new mail notifications do not occur.
Now, Outlook 2010 provides you with full capability to open multiple Exchange mailboxes. All of the mailboxes have full message fidelity and you have access to all of the content in all of those mailboxes (that is, you don’t need a PST for calendars, tasks, contacts, etc.). All of the Exchange mailboxes are treated as primary mailboxes, so you get all your reminders and notifications. All of the Exchange mailboxes can also be cached locally into an OST for speedy offline access.
So, if you have not yet considered an upgrade to Outlook 2010 – I recommend it. This one feature makes it worth the money. Plus, there are lots of other changes to Outlook 2010 that help improve the value proposition even more. You can download a timelocked demo from microsoft.com/office.