I have an RSS feed I'm monitoring for changes. Is there some web service that provides a way to be notified by email immediately** when a new post is added?
** When I say immediately, I mean within 1 - 2 minutes.
George, you need to check if the publisher's feed is pushing its RSS feed with some push protocol; PubSubHubbub for example.
PubSubHubbub is an open protocol for distributed Publish/subscribe communication on the internet. The protocol extends the Atom and RSS protocols for data feeds. The main purpose is to provide near-instant notifications of change updates, which would improve on the typical situation where a client periodically polls the feed server at some arbitrary interval.
You could also register to Superfeedr that handles pushed contents via PubSubHubbub, RSSCloud, XML-RPC or SUP.
Answering some comments, if your feed's publisher does not use this kind of push technology, superfeedr (via polling) guarantee delivery of new entries within 15 minutes of their publication.