sk_filter is an email filter that aims to reduce
costs for dial-up users. Although there are some
other filters out there that claim to do the same,
sk_filter really lets you take control of your
email by helping you filter email messages by
their size. It will let you filter messages that
are equal to or larger than a specific size, or
messages that have a size that falls within a
specified range, or messages of an exact size.