People seem to implement this sort of capability themselves a lot. So there is going to be a small marginal value to a 'canned' version, web sites are also particularly careful with emails and other PII people send them so a service approach runs the risk of the service harvesting that data and reselling it without the web site owners knowledge or approval. And finally, I expect a quick crawl of the web would turn up a zillion different 'tweaks' that individual sites make for their particular application, so it would be hard for them to use a pre-baked one.