Customer environment is exchange 2003 sp2. they found such issue:
outlook 2007 can use autodiscover connnect exchange 2003 in exchange mode.
outlook 2010 can not use autodiscover connect exchange 2003 in exchange mode. Manually is ok.
outlook 2010 do not support exchange 2003
Exchange Server 2003 is the earliest version of Exchange Server that can be used with Outlook 2010.
The Junk E-mail Filter is provided for a subset of Outlook 2010 account types. The types are listed in the following section, Supported account types. The filter works best when it is used with Microsoft Exchange Server 2003 and later versions. Note that Exchange Server 2003 is the earliest version of Exchange Server that can be used with Outlook 2010.
this is a known issue.
manually create Outlook profile (and not use the account auto setup process)