There are various ways in which this task can be done, the simplest one that I can think of would be using the Copy function from MS Excel VBO and then do a Paste Special on the Outlook Message.
Then select whichever format you prefer.
- HTML format will be smallest, but may not 100% capture the Excel look
- Bitmap will be largest, but will 100% capture the Excel look
- Picture should be like the bitmap barring some minor differences
Make sure you have the mail body activated when you are doing the paste, so you are not attempting to paste the contents into the address list.