I'm looking for one as well to run as an extension of the browser. When I use my mac at work, I can't use my mail programs to check my personal emails (firewall) so I can only check via web mail.
I like X-Notifier for Chrome but you can't add iCloud email to it. I also prefer to use Safari but it's not a huge deal. Just trying to find a good webmail checker/notifier that can handle multiple email accounts that can check GMail, iCloud & Yahoo. I think it being a browser extension is key in my instance. All other non-browser based notifier apps don't seem to work at work.
If anyone has a suggestion, it would be much appreciated.
(Also, just a note I'v e tried the Notifier app that isn't being supported anymore and it doesn't seem to work, maybe because of the firewall issue.)