client operation failed on determining TNEF attachment type

[CTDev Team]

Hi,

We are using Exchange Server 5.5, and have applications written in VB6 and
C# that read and process emails.

We are experiencing intermittent errors similar to

C# Application

System.Runtime.InteropServices.COMException (0x80004005): The client
operation failed. [Microsoft Exchange Server Information Store -
[E_FAIL(80004005)]] at System.RuntimeType.ForwardCallToInvokeMember(Strin g
memberName, BindingFlags flags, Object target, Int32[] aWrapperTypes,
MessageData& msgData) at MAPI.Attachment.get_Type()

VB Application

-2147467259 = The client operation failed. [Microsoft Exchange
Server Information Store

The error happens on the determination of the attachment type, as shown in
these code snippets:

C# Application

if ((CdoAttachmentType)att.Type ==
MAPI.CdoAttachmentType.CdoEmbeddedMessage)

VB Application

If CInt(objMessage.Attachments(j).Type) <> CdoEmbeddedMessage Then

As it is, the fact that there are attachments is recognized, but fails in
determining the attachment types.

Please note that we can open the emails and attachments from Outlook without
any problems.

We noticed that this behavior happens for emails with source containing
something similar to:

X-MS-TNEF-Correlator: 00000000FCD67D6733BD374CB183ED8ADF9C0E6BE44E3100
This is a multi-part message in MIME format.
--Boundary_(ID_UMmVtfCC+Dy+KJBXVN6RQg)
Content-type: text/plain; charset=iso-8859-1
Content-transfer-encoding: 7BIT

--Boundary_(ID_UMmVtfCC+Dy+KJBXVN6RQg)
Content-type: application/ms-tnef; name=winmail.dat
Content-transfer-encoding: base64
Content-disposition: attachment; filename=winmail.dat

Any help you can provide to help us understand the problem and work towards
a solutions is greatly appreciated.

Thanks and regards,
Romel