Very useful! What worries me: when this eventually fails, I won't know it's not working anymore (partially the fault of my feedreader, but still).
Hi norswap, Author of Kill the Newsletter! here. That is a valid concern, thanks for bringing it up. I worry about this myself, being the #1 user of the tool. Do you have any idea how to fix it, though? I thought of a dead man’s switch kind of thing, in which I would periodically add an “everything is still working” for low-volume feeds, but I didn’t do it because I would consider such entries spam. What do you think…
I don't really have a better suggestion. Ideally, making sure that the feeds would raise some kind of error condition in all feed readers, but I doubt there's something universal like that.
Maybe the "still working" message is good enough, it wouldn't bother me too much, personally.