Microsoft Outlook: Invisible attachments

Few of Outlook clients (2007/2013 in my case) don`t see forwarded attachments from colleagues within same Exchange 2013 organization. It doesn`t happen to all clients, just few. Person forwards attachment but recipient doesn`t see it. If person who sends attachment looks into Sent Items, paperclip can be seen but no attachment inside mail. Paperclip can be seen everywhere, but there is no attachment in email. Attachment can be seen if you open email on smartphone email client.

If you have problem that is similar to the description above, here is what you need to do.

In description of email paperclip can be seen


When you open email, attachment cannot be seen in the place where it usually is


From all other colleagues attachments arrive normally and can be seen.

Problem is in your Exchange configuration. I’m working on Exchange 2013 so here is what you need to do on it.

What you need to do is add following line to your EdgeTransport.exe.config file:

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

Here is the whole procedure:

First – stop Microsoft Exchange Transport Service


Open C:\Program Files\Microsoft\Exchange Server\V15\Bin\EdgeTransport.exe.config file. It is recommended to do backup of file before editing it.

Somewhere between <appSettings> and </appSettings> in file enter line that I already mentioned

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


Save changes to a file and start Exchange Transport Service.

Test with problematic Outlook client by forwarding mail with attachment. It should work, in my case it is working.