mistakenly labeling messages

If I accidentally mark a valid message as spam, or vice-versa, is the harm to the filter undone if I mark the same message again, correctly?

If not, is there a way to undo the harm?

Or is it better to leave the mistake alone, rather than compounding the error by marking the same message again, differently?

If I make this kind of mistake occasionally, how badly are the filter rules damaged?

Thanks in advance,

Tim

The harm to the corpus is undone. If marking the valid message as spam caused SpamSieve to disable some whitelist rules, you might want to open the whitelist window and re-check them.

So long as you correct the corpus by marking the message correctly, you probably wouldn’t notice any decline in accuracy.