FeedmailPro sent an email to its over 200 blog customers that they will be shutting down and stop providing services as of December 1st 2010. Their recommendation is to migrate your RSS to Email accounts over from FeedmailPro to MailChimp.
This news hits me as I had converted my Feedburner accounts to FeedmailPro and will have to figure out how to migrate the 181 or so accounts subscribed to my own blog from FeedmailPro. I still have another hundred something accounts subscribed to my blog from Feedburner as well. MailChimp is a good option for a mailing list as I have mentioned several times before. However, though Mailchimp allows you 1,000 free subscriptions in your list, it only allows you to send a total of 6,000 emails per month for free. So if you use MailChimp as your RSS subscription you will probably require an upgrade to a paid Mail Chimp account, as lets say 300 RSS subscribers * 30 emails per month for a blog that updates daily would equal 9,000 emails sent in one month which is over the 6k free allowance.
If you want to stay free instead of having to pay for an RSS to Email service, then I recommend switching your feed back to Feedburner and notifying your subscribers. Still if you already use MailChimp like I do, there are advantages to having both your mailing list and RSS feed on MailChimp such as being able to send manual email updates to your RSS subscribers and have more visibility and control into your email subscribers.
For my case, I am not ready to commit to a monthly fee yet and sent a notification to my email subscribers to resubscribe via Feedburner. In the meantime, I disabled my FeedmailPro feeds and am done with the service.