iPhone mail fecthing time < 15 minutes Is it possible to set iPhone mail fecthing time &lt; 15 minutes under iOS 5?

The current configuration only allows 15 minutes data pushing, but I need to react to my mail fast. Is there a way to get around this or an application that could help this?
Set Push to ON (under settings->Mail, Contacts, Calendar->Fetch New Data). You can even select push or pull for each single mail account under Advanced.