The really annoying thing about spam is not that we are wasting our bandwidth to process it, but false positives – messages which our anti spam software decided they are spam while they where totally legit.This hurts is both as receivers and senders, we can never be sure if we haven’t missed a great business offer because it was marked as spam, or that the message that we sent asking for urgent help, from someone who should be inclined to helping us, was not ignored but lost cause it looked like spam.
In the email world you can at least ask for auto respond when the email was read. Not a great indication as it is impossible to know if the email was marked as spam or someone is impolite or just can’t be bothered with clicking the button which will send the auto respond indication.
In the blog comment world, and contact pages we don’t even have that, you can’t even ask to be notified if your comment/contact message got into the read queue instead of the spam queue.
In the email world it is impossible to let the sender know if the email was declared spam because the sender part of the email is always spoofed by the spammer and if you will send to the “sender” an automatic message telling him that his message was declared spam, you will bombard unsuspecting people which don’t even know that you exist with this messages.
Websites are in better position as the HTTP protocol force you to send a reply, so why not send something like “sorry but my stupid and out of date anti spam software decided your comment is a spam” when a comment is declared as spam? spam bots will probably ignore it but legit commenter will know that they should not expect the comment to be published, and if they have to, they can try contacting the site owner by other means.