We are currently evaluating YouTrack and in our setup, there is a lot of e-mail communication going on. Issues are very often reported by email and have rich formatting - error report details are in tabular format, images are embedded in context of the message... Simply said - whatever you may expect from an email, it is there.
Issues created from emails are plain text, and with all formatting gone, they are unreadable.
If issue is entered manually, there is a lack of rich text editor, where one could simply copy-paste formatted text.
YouTrack does not seem to support HTML at all, which is too bad, but is there any way that users should handle such scenario?