ok, i fixed the problem for the next release (coming very soon, 2.3f), and you will be able to check %item-size-kb% in the [upload completed]
So, if you want to set a limit to 1MB, you should check if it's more than 1000.
I added a specific capability to it, and it's to refuse uploads. Any text that you will give will be considered a reason for refusal and the file will automatically be deleted.
This is an example
[upload completed]
{.if|{.%item-size-kb% > 500.}|Sorry, limit of 500KB.}