Hi Marc,
I just wanted to confirm that the issue is when you email out a record to a user and they view an embedded report on that record the embedded report is difficult to read? What seems to cause the most issue the volume of records, the size of the report with all the fields, or just the general appearance of the report? If it is an overload of information that might not all be relevant it is possible to make a version of the form that uses a report with less fields for emailing out to narrow down the number of fields and simplify their view. The same can be done with more filtering or grouping on the report to help control an overload of records.