Is it possible to time adjust push mail on my iPhone? What I want is that the phone automatically adjust the push setting for some time slots a day. E.g. that it should push mail between 9-17, but after 17 it should not push mail for an account. Is there an app for that?
There is no simple app for this in the default Mail app as unfortunately there is no way for an app to change this setting. You either have to accept notifications all of the time, or manually turn them on/off in the Settings app every time you want to change them as @afragen said.
There may be other email apps that will provide this functionality, but I've not come across any.
This isn't currently an option, but in iOS 6, Notifications will have a "Do Not Disturb" feature, so you can mute them at certain hours of the day. It won't stop your phone from receiving mail, but the alerts won't bother you.
Turn off Notifications from the Settings > Notifications tab. Search for Mail and turn off all notification settings.
If you also want you might need to go to Settings > General > Sounds and turn off the New Mail sound.
It might be possible to set your home WiFi router to disable internet access in general or for a specific device or specific service (like Mail) during certain hours. This would normally be under a Parental Controls section of the router setup.