The Feed Is in the Mail
Even some the best RSS clients lack compelling archiving features -- older headlines drop out of sight after a day or two. Thankfully, sites like RMail and RSSfwd provide simple archiving by delivering feeds to your e-mail account.
...emails are sent every hour, on the hour, at most one email per hour.
Absolutely nothing wrong with that policy. A conscious decision to protect the subscriber's mailbox. However, it also means that if you've subscribed to high traffic feeds for archival purposes, you'd be in for a little surprise when you discover your archive isn't anywhere complete. (Note below: Highlighted are emails from Rmail, the rest is from RssFwd. Both are subscriptions to the same Slashdot feed.)
There are really many RSS-to-Email services out there. Some has accounts and passwords, some can only be used for certain feeds only, some sends 1 email daily unless you pay, many has complex features, and there are some which simply sends an email for each update. Each serve its own target audience. Do make sure you are the correct audience.