MAPI.Fields E_Fail error

Hi all,

I have created an outlook form which has some "User-defined fields in
this item". When the user use this form, these fields will be set
depends on the interaction on this form.

When the user send this form to me, I can read it (via) outlook and
also the corresponding user-defined fields. I have created a .net win
service to monitor my inbox for all these forms. Within the .net win
service, I retrieve these user-definied fields using the following
methods:-

mMsgCur.Fields.Item("UserDefinedFld1").value
mMsgCur.Fields.Item("UserDefinedFld2").value

where mMsgCur is a current message in the inbox.

These lines are okay when the sender is from the same domain , e.g
my email account is xxxx@abc123.com
the sender account is yyyy@abc123.com

When the sender account is from another domain , ie
zzzz@123abc.com, these 2 lines fail and reported an [E_FAIL(80004005)]

I am not sure whether this got something to do with security. If I use
Outlook to open it, I can see all these user-defined fields regardless
the sender domain.

OS : W2K
Exchange : 6
Outlook : Outlook XP

Does anyone have any idea?

Thanks in advance

Kevin