Use web1 as an example
MailboxeFormControl
Enable the tick box: MAI:AutoResponse
Add mail:autoresponsetext to the reset list on the 'client-side' tab.
Now when you run you prog, go into the form and click on the autoresponse tick box
"</div>" will be inserted in the text box field.
This only seems to happen to firefox. Safari/Chrome/IE all behave correctly. And I have run firefox in safe mode to make sure it isn't connected to an add on.