The one domain (domain a) has an exchange environment installed.
The other domain (domain b) makes use of a hosted exchange environment in another facility.
For some reason or other when outlook is opened in domain b, it continually attempts to logon to the exchange environment in domain a.
What happens is Outlook establishes a connection to the hosted exchange environment mailbox and mail flows, but every 15 to 30 minutes a login box pops up asking for credentials for the exchange environment in domain a.
How do I stop this from happening as it is causing users huge frustration.