fastmail.fm is the standard against which all free webmail filtering is measured. gmail fail, yahoo fail, hotmail fail.
both yahoo mail and gmail provide the facility for 3rd party application development. Why are there no pure-user controlled applications with the power of exim — short of bounce? Although I would dearly love to have a bounce action in filters.
[insert fastmail.fm filtering screenshot here]
[insert cpanel/exim gui screenshot here]
[insert cpanel exim filterset xml screenshot here]