Consider the following scenario:
You create an HTML email that contains several inline pictures in Microsoft Outlook in a Microsoft Exchange Server 2013 environment that has cumulative update 9 installed.
You try to smart forward the email to another user by using an iOS synced device. So you select the Include option for attachments when you're prompted for forwarding.
The email is received by another user in Outlook or Microsoft Outlook Web App.
In this scenario, the inline pictures are attached as traditional attachments. Additionally, the original inline attachments are displayed as red circles in the HTML body.
This is a known issue in Exchange Server 2013.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.