So we just launched our iOS client for Harakirimail. You can get it here:
https://itunes.apple.com/us/app/harakirimail/id633675820
Something we added was a custom url scheme. So what does this mean? Well it means that you can enter a special url: harakirimail://inbox/myinbox and if you have the app installed it will open that inbox. So instead of typing http:// you use harakirimail://.
This means that other apps (or websites or you can try it yourself by typing in a harakirimail:// address in safari on your iOS device) can launch our app by linking to harakirimail://, or go to a inbox by opening harakirimail://inbox/<inboxname>.
We have implemented this on https://harakirmail.com using the apple-itunes-app meta Tag or smart app banner. Basicly it is a tag we have in our html. And if you visit harakirimail it will show a banner at the top asking if you want to download the app or open it if you have the app already installed. And if you visit a inbox on the website on an iOS device it will ask you if you want to open the app and if you do. The inbox you visited on the website will be opened in the app, neat huh :)
(read more here: https://developer.apple.com/library/ios/#documentation/AppleApplications/Reference/SafariWebContent/PromotingAppswithAppBanners/PromotingAppswithAppBanners.html)
For the moment we support two paths:
Open a specific inbox in the app:
harakirimail://inbox/<inboxname>
ex: harakirimail://inbox/myinbox
Open a specific email in the app:
harakirimail://email/<email-id>
ex: harakirimail://email/51ab87a42f9f80af680023b2
In the future we will add more paths as we update the service.