If you post the agent code, we may be better able to help. I assume your question really is, how do I write the agent so that it doesn’t cause this problem, not, how do I view this one email?
The error message is “too many paragraphs”. You might try to reduce the number of paragraphs, e.g. by creating a less verbose report, or combining on one line things that are now split on multiple lines, or by using line breaks instead of paragraph breaks (boolean argument to AddNewLine method). See ReportGenerator Class - Lotusscript / Example Code.
A call to the Compact method of NotesRichTextItem, before you send, might also help.
I’m afraid you’ll have to write a LS utility to achieve this (using CopyItemToDocument to transfer each RT field individually to another separate doc).