I am facing problem with many outlook users. We are using Exchange mails and when opening any mail sent or received. In the list view it shows that the mail has attachment but in detail view it is not visible.

if the same mail is opened in mobile device or OWA the attachment is visible.

Tried to disable add-ons or even the Anti Virus but it doesn't help.

Hi,

If we forward the email from mobile device or OWA to yourself does it then show?

Can you checked the headers of the emails to see if they are received with "Content-Type: multipart/related;"? To check this, open the email and click File > Info > Properties. Check the Internet Headers field.

If the header shows "Content-Type: multipart/related;", please try to setup a transport rule to change these back to multipart/mixed as per the below:

1. Launch Exchange Management Console

2. Expand Organization Configuration, and select Hub Transport

3. On the right-hand Action Pane, select New Transport Rule

4. Give the rule a name (Ex:- Paperclip icon not showing)

5. Select when the message header contains text patterns, click the highlighted message header, Type "Content-Type" click OK, and then click the highlighted text patterns, Type "multipart/related" click Add, click OK, and then click Next

6. Select set header with value, click the highlighted header text, type Content-Type, click OK

7. Click the highlighted value text, type multipart/mixed, click OK, and then click Next.

8. On the Exceptions page, simply click next

9. At the final Create Rule page, click New, and then click Finish

A similar issue discussed here: https://social.technet.microsoft.com/Forums/office/en-US/5ddd2f7f-9613-4744-ada5-9893d58cd18b/outlook-not-showing-attachment-owa-does?forum=exchangesvrclientslegacy

We can also have a look at the following KB article and check if it applies to your scenario:

https://support.microsoft.com/en-us/kb/954684

Please let me know the result.

Regards,

Steve Fan
TechNet Community Support