Attachment does not show in Outlook 2010, but shows in Outlook 2003

How to restore attachments for Multi-part related messages in exchange 2010.

An unique issue was discovered when receiving “Multi-part related messages” when sent to 2 users on differing exchange versions (E2003 and E2010). Discovered with Exchange 2003 - 2010 coexistence environment.

The Symptoms: A user with Exchange 2010 mailbox will not see the attachments but when they forward the message, the attachment will appear. The same user will be able to see the attachments in OWA, however, only if they are not using conversation view.

A user on Exchange 2003 will see the attachment and can forward without issues.

The Cause: These type of emails come to us in this format. Headers from mailgate will show that there is an attachment, yet the headers will show that there isn’t an attachment via the “X-MS-Has-Attach:”  parameter being blank and showing content as “yes” on exchange 2003 mailboxes.

In this case, the reason the attachment was hidden in Outlook was because of 2 things:

1. Content-Type: multipart/related - Outlook is unable to display attachments that have this content-type

2. PR_ATTACHMENT_HIDDEN = True

The Resolution: Give yourself full mailbox access to the users account. Open MFCMAPI.exe (you can download this from www.codeplex.com). 

NB: Only run MFCMAPI.exe if you are experienced with this tool. It is a powerful tool to work with. I ran this under Microsofts instruction.

Run this and when open go to Session> Logon and display Store table>

(select your profile name in the next box)

Double click on the profile name. EG: Matthew Robertson.

A new dialogue box will open. Drill down to Root Container> Top of information store > Inbox (double click).

Locate the email in the inbox folder and sort the property Names. Locate “PR_ATTACHMENT_HIDDEN = True “

(NB: because I have already done this change, for this example we will need to access another field “PR_HASATTACH” because the prior field has changed and is now removed.) “PR_HASATTACH” double click on this property.

Check the Boolean box, click OK.

Close out of MFCMAPI. Restart Outlook and check to make sure the attachments have appeared in the email. Paperclip icon might not be showing, but your attachments will.

The Permanent Resolution: As Microsoft says this is a known issue to them and there is a configuration change we can make on Exchange 2010 to make sure that future “Multi-part related messages” will show in exchange 2010, IE: To permanently set the value of "TreatInlineDispositionAsAttachment" as “True”

Exchange Server 2010

1.      Stop the Exchange Transport service.

2.      Locate the EdgeTransport.exe.config file. This file is located in the following path: 

<drive> :\Program Files\Microsoft\Exchange Server\Bin\

3.      In the EdgeTransport.exe.config file, add the following entry between the <appSettings> element and the </appSettings> element:

<add key="TreatInlineDispositionAsAttachment" value="true" />

4.      Restart the Transport service.

REF: http://support.microsoft.com/kb/954684