To set your table so that it has inside borders but no outside borders, add a FRAME<TABLE ...>FRAMEFRAMEVOID.
<TABLE border="1" bordercolor="#CBD3E1" bgcolor="#F1F4F5" RULES=ALL FRAME=VOID>
which gives us this table:
| watermelon | grapes |
| peaches | bananas |
Table Borders: Just Rows or Just Columns >>>