If the incoming emails has embedded images and with content ID in the email body, for example:

Email body 
[cid:image001.jpg@01CDFF88.D12EE900]

Those CID will be displayed in the issues description with the newly created issues.

Steps to Reproduce:

1. Open Outlook 2010, create a new email, drag and drop any image from the browser to Outlook or copy any image from the browser and paste into the email body in Outlook, see : http://community.office365.com/en-us/forums/161/t/57207.aspx
2. Send the email to the JIRA instance to create an issue.

Expected Behavior:
The issue is created and the images attached to the ticket. The issue description should only contains the email body without any weird strings.

Actual Behavior:
The issue is created and the images attached to the ticket. The issue description contains the CID for the images, i.e:

Email body 
[cid:image001.jpg@01CDFF88.D12EE900]

Workaround:

The JEMH now features a workaround for this:

https://marketplace.atlassian.com/plugins/com.javahollic.jira.jemh-ui

Alternatively, use the Insert button in Outlook instead of 'drag and drop' or 'copy-paste'. Another way, is to include the images as attachments.