This issue is resolved in Mimecast for Outlook v7.0 R1 onwards.
It has been identified that when sending Feedback, the Enter / Return key is not functioning as expected.
- Mimecast for Outlook v7.0 (Build 7.0.1762.17740)
When entering text in the Send Feedback text box, pressing the Enter / Return key sends the feedback rather then adding a carriage return.
Do not use Enter / Return key when adding feedback. Word wrapping is enabled in the text box.