I assume you want to put a checkbox where you have the <INPUT TYPE=CHECKBOX NAME="maillist"> tag? You need to place that inside of a set of table data tags:
In your code sample, the input tag is between table row tags, but not inside a table data tag. I'm not sure what the (X)HTML specifications say to do (if anything since it is technically incorrect markup), but most browsers will render anything placed between <table> tags, but not inside of <td> (table data) or <th> (table header) tags before the table. Some browser may even ignore such erroneous entities.