I just want to send a webmention that is a plain notification, without any special semantics associated with "liking", "bookmarking", or "replying." The webmention spec suggests this is the primary purpose, but when I try to send a vanilla webmention to webmention.io, I get errors complaining that various microformats are not implemented on the source website, and the only available microformats are "like", "reply", "repost" etc. with no simple "mention" option.

What should I do in this situation?