Here's the main sentence:

I'd recommend that you should consider keeping some users on Exchange.

Here's the clarifying, qualifying, appositional or 'extra' information (I'm in the habit of calling them appositional phrases, but I know that in other parts of the world people might use another term):

...if you have executives that live and die with Outlook...

This phrase above is the phrase that you would set off with commas, as in:

I'd recommend that, if you have executives that live and die with Outlook, you should consider keeping some users on Exchange.

You can see how this appositional phrase can be moved around in the examples below:

If you have executives that live and die with Outlook, I'd recommend that you should consider keeping some users on Exchange.

I'd recommend that you should consider keeping some users on Exchange, if you have executives that live and die with Outlook.

When working with a style guide that calls for a minimalist approach to punctuation, I suppose that you could argue that all of these examples could go without. The problem with minimalism in these cases is that ultimately decisions rest on 'necessity by reason of clarity,' but one person's clarity is not always another's, and therefore, there is always some ambiguity. Based on traditional rules of standardization, all the commas here would be required/recommended.