While they don't explicitly identify them as such, the content of the e-mail is essentially a DMCA notification. Since the content is not stored on the ISP's systems, and is just a transitory communication over the ISP's network, the ISP is not obligated to perform any action whatsoever. They could >/dev/null 2>&1 them and there's nothing the RIAA could do about it.
To be valid, the DMCA notification needs to be directed to the party hosting the content, in this case the end-user. The ISP for that user is not obligated to 'pass on' the notification to the end user any more than they would be to 'pass on' a notification meant for another ISP. It is the complainants responsibility to identify the correct destination for the DMCA notification, not anyone else's.
Even _if_ the ISP were hosting the content on systems they own, the only obligation they would have would be to remove the specifically identified offending content from their systems. Per the DMCA, the alleged offender would have 10 days to contest the validity of the DMCA notification at which point the ISP would be required to re-post the content if they did so. The claimant would then need to begin legal proceedings to obtain further relief.
Seems to me to be a re-hash of a previously failed tactic. Once the RIAA found this was a dead-end, they began their DOE lawsuits.