"Lanwench [MVP - Exchange]"
In
Remove your mail account in Outlook, or change it, or don't open Outlook.
The default mail handler doesn't mean that other clients can't be
configured to pick up mail for account X - just that when you click on a
mailto: link, etc., the default client will launch.
In addition, you can configure Outlook to NOT perform scheduled mail polls.
You could also configure the Send/Receive Group to EXCLUDE (i.e., uncheck)
any acocunts that you choose to leave defined in Outlook but do not want to
include in automatic mail polls. That way, you could have OE automatically
poll some accounts and Outlook to poll others.
As Lanwench said but paraphrased, setting one as the default does NOT mean
all others are disabled. Default just means default, not disabled for
everything else.