Mailbox is one of the most popular mail clients for iPhone. It essentially helps users organize emails to increase productivity, in addition to reaching the coveted "inbox zero".
As a result of the immense demand, the developers instituted a "wait in line" feature until they could get the infrastructure in order to handle the server stress. Now it appears they are ready to include even more users with the release of an iPad app.
Mailbox for iPad has the same gesture-based email management system found on the iPhone, but is optimized for the larger iPad screen and is available now in iTunes.
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